A policeman stands near the scene where a truck speeded into a christmas market in Berlin, on December 19, 2016 killing nine persons and injuring at least 50 people. / AFP PHOTO / John MACDOUGALLJOHN MACDOUGALL/AFP/Getty Images

Police blocks a road leading to a scene where a truck speeded into a christmas market in Berlin, on December 19, 2016 killing at least one person and injuring at least 50 people. / AFP PHOTO / John MACDOUGALLJOHN MACDOUGALL/AFP/Getty Images

People stand at the scene where a truck speeded into a christmas market in Berlin, on December 19, 2016 killing nine persons and injuring at least 50 people. / AFP PHOTO / John MACDOUGALLJOHN MACDOUGALL/AFP/Getty Images

Police blocks a road leading to a scene next to the Gedächniskirche church where a truck crashed into a christmas market in Berlin, on December 19, 2016 killing at least nine people and injuring at least 50 people. / AFP PHOTO / Odd ANDERSENODD ANDERSEN/AFP/Getty Images

Ambulances arrive on a road leading to a scene next to the Gedächniskirche church where a truck crashed into a christmas market in Berlin, on December 19, 2016 killing at least nine people and injuring at least 50 people. / AFP PHOTO / Odd ANDERSENODD ANDERSEN/AFP/Getty Images

Ambulances arrive at the scene where a truck speeded into a christmas market in Berlin, on December 19, 2016 killing nine persons and injuring at least 50 people. / AFP PHOTO / Odd ANDERSENODD ANDERSEN/AFP/Getty Images

BERLIN, GERMANY - DECEMBER 19: An ambulance drives near the area after a lorry truck ploughed through a Christmas market on December 19, 2016 in Berlin, Germany. Several people have died while dozens have been injured as police investigate the attack at a market outside the Kaiser Wilhelm Memorial Church on the Kurfuerstendamm and whether it is linked to a terrorist plot. (Photo by Sean Gallup/Getty Images)

BERLIN, GERMANY - DECEMBER 19: Police stand near the area after a lorry truck ploughed through a Christmas market on December 19, 2016 in Berlin, Germany. Several people have died while dozens have been injured as police investigate the attack at a market outside the Kaiser Wilhelm Memorial Church on the Kurfuerstendamm and whether it is linked to a terrorist plot. (Photo by Sean Gallup/Getty Images)

BERLIN, GERMANY - DECEMBER 19: An ambulance and rescue workers arrive to the area after a lorry truck ploughed through a Christmas market on December 19, 2016 in Berlin, Germany. Several people have died while dozens have been injured as police investigate the attack at a market outside the Kaiser Wilhelm Memorial Church on the Kurfuerstendamm and whether it is linked to a terrorist plot. (Photo by Sean Gallup/Getty Images)

BERLIN, GERMANY - DECEMBER 19: Ambulances are parked near the area after a lorry truck ploughed through a Christmas market on December 19, 2016 in Berlin, Germany. Several people have died while dozens have been injured as police investigate the attack at a market outside the Kaiser Wilhelm Memorial Church on the Kurfuerstendamm and whether it is linked to a terrorist plot. (Photo by Sean Gallup/Getty Images)

BERLIN, GERMANY - DECEMBER 19: Police cars line up the area after a lorry truck ploughed through a Christmas market on December 19, 2016 in Berlin, Germany. Several people have died while dozens have been injured as police investigate the attack at a market outside the Kaiser Wilhelm Memorial Church on the Kurfuerstendamm and whether it is linked to a terrorist plot. (Photo by Sean Gallup/Getty Images)

BERLIN, GERMANY - DECEMBER 19: Police speak to an ambulance near the area after a lorry truck ploughed through a Christmas market on December 19, 2016 in Berlin, Germany. Several people have died while dozens have been injured as police investigate the attack at a market outside the Kaiser Wilhelm Memorial Church on the Kurfuerstendamm and whether it is linked to a terrorist plot. (Photo by Sean Gallup/Getty Images)

Policemen stand at the site where a truck speeded into a christmas market in Berlin, on December 19, 2016 killing nine persons and injuring at least 50 people. / AFP PHOTO / Odd ANDERSENODD ANDERSEN/AFP/Getty Images

BERLIN, GERMANY - DECEMBER 19: Rescue workers arrive to the area after a lorry truck ploughed through a Christmas market on December 19, 2016 in Berlin, Germany. Several people have died while dozens have been injured as police investigate the attack at a market outside the Kaiser Wilhelm Memorial Church on the Kurfuerstendamm and whether it is linked to a terrorist plot. (Photo by Sean Gallup/Getty Images)

Policemen stand near the site where a truck speeded into a christmas market in Berlin, on December 19, 2016 killing nine persons and injuring at least 50 people. / AFP PHOTO / John MACDOUGALLJOHN MACDOUGALL/AFP/Getty Images

BERLIN, GERMANY - DECEMBER 19: Rescue workers arrive to the area after a lorry truck ploughed through a Christmas market on December 19, 2016 in Berlin, Germany. Several people have died while dozens have been injured as police investigate the attack at a market outside the Kaiser Wilhelm Memorial Church on the Kurfuerstendamm and whether it is linked to a terrorist plot. (Photo by Sean Gallup/Getty Images)

A policeman stands near the site where a truck speeded into a christmas market in Berlin, on December 19, 2016 killing nine persons and injuring at least 50 people. / AFP PHOTO / John MACDOUGALLJOHN MACDOUGALL/AFP/Getty Images

Police blocks a road leading to the site next to the Gedächniskirche church (background) where a truck crashed into a christmas market in Berlin, on December 19, 2016 killing at least nine people and injuring at least 50 people. / AFP PHOTO / Odd ANDERSENODD ANDERSEN/AFP/Getty Images

Police guard a Christmas market after a truck ran into the crowded Christmas market in Berliin Berlin, Germany, Monday, Dec. 19, 2016. (AP Photo/Michael Sohn)

Police blocks a road leading to the site next to the Gedächniskirche church (background) where a truck crashed into a christmas market in Berlin, on December 19, 2016 killing at least nine people and injuring at least 50 people. / AFP PHOTO / Odd ANDERSENODD ANDERSEN/AFP/Getty Images

Police stand beside a damaged truck which ran into crowded Christmas market in Berliin Berlin, Germany, Monday, Dec. 19, 2016. (AP Photo/Michael Sohn)

Rescue forces stand near the site where a truck speeded into a christmas market in Berlin, on December 19, 2016 killing nine persons and injuring at least 50 people. / AFP PHOTO / Odd ANDERSENODD ANDERSEN/AFP/Getty Images

Rescue forces stand near the site where a truck speeded into a christmas market in Berlin, on December 19, 2016 killing nine persons and injuring at least 50 people. / AFP PHOTO / Odd ANDERSENODD ANDERSEN/AFP/Getty Images

Police blocks a road leading to the site next to the Gedächniskirche church where a truck crashed into a christmas market in Berlin, on December 19, 2016 killing at least nine people and injuring at least 50 people. / AFP PHOTO / Odd ANDERSENODD ANDERSEN/AFP/Getty Images

Rescue forces work at the site where a truck speeded into a christmas market in Berlin, on December 19, 2016 killing nine persons and injuring at least 50 people. / AFP PHOTO / Odd ANDERSENODD ANDERSEN/AFP/Getty Images

Rescue forces work at the site where a truck speeded into a christmas market in Berlin, on December 19, 2016 killing nine persons and injuring at least 50 people. / AFP PHOTO / Odd ANDERSENODD ANDERSEN/AFP/Getty Images

A police man stands at the site where a truck speeded into a christmas market in Berlin, on December 19, 2016 killing nine persons and injuring at least 50 people. / AFP PHOTO / John MACDOUGALLJOHN MACDOUGALL/AFP/Getty Images

Police blocks a road leading to the site next to the Gedächniskirche church (background) where a truck crashed into a christmas market in Berlin, on December 19, 2016 killing at least nine people and injuring at least 50 people. / AFP PHOTO / Odd ANDERSENODD ANDERSEN/AFP/Getty Images

Police and ambulances are standing around the site next to the Gedächniskirche church (background) where a truck crashed into a christmas market in Berlin, on December 19, 2016 killing at least nine people and injuring at least 50 people. / AFP PHOTO / Odd ANDERSENODD ANDERSEN/AFP/Getty Images

Berlin's mayor Michael Mueller (4R) walks at the site where a truck speeded into a christmas market in Berlin, on December 19, 2016 killing nine persons and injuring at least 50 people. / AFP PHOTO / Odd ANDERSENODD ANDERSEN/AFP/Getty Images

In this screen grab taken from video, emergency services attend the scene, after an attack by a truck at a Christmas market, in Berlin, Monday, Dec. 19, 2016. German media are reporting a truck has run into a crowded Christmas market in the center of Berlin, causing multiple injuries. Both the Berliner Zeitung newspaper and the Berliner Morgenpost reported the truck ran into the market outside the landmark Kaiser Wilhelm Memorial Church on Monday evening. (AP)

A policeman walks at the site where a truck speeded into a christmas market in Berlin, on December 19, 2016 killing nine persons and injuring at least 50 people. Ambulances and police rushed to the scene after the driver drove up the pavement of the market in a central square popular with tourists less than a week before Christmas, in a scene reminiscent of the deadly truck attack in Nice. / AFP PHOTO / Odd ANDERSENODD ANDERSEN/AFP/Getty Images

Firefighters attend an injured person after a truck ran into crowded Christmas market in Berlin, Germany, Monday, Dec. 19, 2016. Police said that several people have been killed. (AP Photo/Michael Sohn)

Police and firefighters are standing around the site next to the Gedächniskirche church (background) where a truck crashed into a christmas market in Berlin, on December 19, 2016 killing at least nine people and injuring at least 50 people. / AFP PHOTO / John MACDOUGALLJOHN MACDOUGALL/AFP/Getty Images

A firefighter walks past a star after a truck ran into crowded Christmas market in Berlin, Germany, Monday, Dec. 19, 2016, killing several people. (AP Photo/Michael Sohn)

Rescue forces work at the truck that crashed into a Christmas market in Berlin, on December 19, 2016 killing nine persons and injuring at least 50 people. AFP/Getty Images

BERLIN, GERMANY - DECEMBER 20: German Chancellor Angela Merkel (R) and Foreign Minister Frank-Walter Steinmeier depart after laying flowers near where yesterday a lorry ploughed through a Christmas market on December 20, 2016 in Berlin, Germany. So far 12 people are confirmed dead and 45 injured. Authorities have confirmed they believe the incident was an attack and have arrested a Pakistani man who they believe was the driver of the truck and who had fled immediately after the attack. Among the dead are a Polish man who was found on the passenger seat of the truck. Police are investigating the possibility that the truck, which belongs to a Polish trucking company, was stolen yesterday morning. (Photo by Sean Gallup/Getty Images)

BERLIN, GERMANY - DECEMBER 20: (L-R) Mayor of Berlin, Michael Muller, German Chancellor Angela Merkel, German Interior Minister Thomas de Maiziere and Forign Minister Frank-Walter Steinmeier lay flowers near where yesterday a lorry ploughed through a Christmas market on December 20, 2016 in Berlin, Germany. So far 12 people are confirmed dead and 45 injured. Authorities have confirmed they believe the incident was an attack and have arrested a Pakistani man who they believe was the driver of the truck and who had fled immediately after the attack. Among the dead are a Polish man who was found on the passenger seat of the truck. Police are investigating the possibility that the truck, which belongs to a Polish trucking company, was stolen yesterday morning.(Photo by Sean Gallup/Getty Images)

German Chancellor Angela Merkel (C), German Foreign Minister Frank-Walter Steinmeier (L) and Berlin's mayor Michael Mueller (C) walk through the Christmas market of the Kaiser-Wilhelm-Gedaechtniskirche (Kaiser Wilhelm Memorial Church), the day after an attack at the nearby Christmas market in central Berlin, on December 20, 2016. German police said they were treating as "a probable terrorist attack" the killing of 12 people when the speeding lorry cut a bloody swath through the packed Berlin Christmas market. / AFP PHOTO / Tobias SCHWARZTOBIAS SCHWARZ/AFP/Getty Images

BERLIN, GERMANY - DECEMBER 20: German Chancellor Angela Merkel (R) and Foreign Minister Frank-Walter Steinmeier depart after laying flowers near where yesterday a lorry ploughed through a Christmas market on December 20, 2016 in Berlin, Germany. So far 12 people are confirmed dead and 45 injured. Authorities have confirmed they believe the incident was an attack and have arrested a Pakistani man who they believe was the driver of the truck and who had fled immediately after the attack. Among the dead are a Polish man who was found on the passenger seat of the truck. Police are investigating the possibility that the truck, which belongs to a Polish trucking company, was stolen yesterday morning. (Photo by Sean Gallup/Getty Images)

German Chancellor Angela Merkel (C), German Foreign Minister Frank-Walter Steinmeier (L) and Berlin's mayor Michael Mueller (C) walk through the Christmas market of the Kaiser-Wilhelm-Gedaechtniskirche (Kaiser Wilhelm Memorial Church), the day after an attack at the nearby Christmas market in central Berlin, on December 20, 2016. German police said they were treating as "a probable terrorist attack" the killing of 12 people when the speeding lorry cut a bloody swath through the packed Berlin Christmas market. / AFP PHOTO / Tobias SCHWARZTOBIAS SCHWARZ/AFP/Getty Images

BERLIN, GERMANY - DECEMBER 20: (L-R) Mayor of Berlin, Michael Muller, German Chancellor Angela Merkel, German Interior Minister Thomas de Maiziere and Forign Minister Frank-Walter Steinmeier lay flowers near where yesterday a lorry ploughed through a Christmas market on December 20, 2016 in Berlin, Germany. So far 12 people are confirmed dead and 45 injured. Authorities have confirmed they believe the incident was an attack and have arrested a Pakistani man who they believe was the driver of the truck and who had fled immediately after the attack. Among the dead are a Polish man who was found on the passenger seat of the truck. Police are investigating the possibility that the truck, which belongs to a Polish trucking company, was stolen yesterday morning.(Photo by Sean Gallup/Getty Images)

BERLIN, GERMANY - DECEMBER 20: German Chancellor Angela Merkel (2nd from R) looks on as Foreign Minister Frank-Walter Steinmeier signs a book of condolences at the Kaiser Wilhelm Memorial Church the day after a truck drove into an adjacent, crowded Christmas market on December 20, 2016 in Berlin, Germany. So far 12 people are confirmed dead and 45 injured. Authorities have confirmed they believe the incident was an attack and have arrested a Pakistani man who they believe was the driver of the truck and who had fled immediately after the attack. Among the dead are a Polish man who was found on the passenger seat of the truck. Police are investigating the possibility that the truck, which belongs to a Polish trucking company, was stolen yesterday morning. (Photo by Sean Gallup/Getty Images)

A Muslim mam prays at a makeshift memorial for the attack victims, on December 20, 2016 in front of the Kaiser-Wilhelm-Gedaechtniskirche (Kaiser Wilhelm Memorial Church) in Berlin, where a truck crashed into a Christmas market. Twelve people were killed and almost 50 wounded, 18 seriously, when the lorry tore through the crowd on December 19, 2016, smashing wooden stalls and crushing victims, in scenes reminiscent of July's deadly attack in the French Riviera city of Nice. / AFP PHOTO / John MACDOUGALLJOHN MACDOUGALL/AFP/Getty Images

German Interior Minister Thomas de Maiziere signs the book of condolences on December 20, 2016 inside the Kaiser-Wilhelm-Gedaechtniskirche (Kaiser Wilhelm Memorial Church), the day after an attack at the nearby Christmas market in central Berlin. German police said they were treating as "a probable terrorist attack" the killing of 12 people when the speeding lorry cut a bloody swath through the packed Berlin Christmas market. / AFP PHOTO / POOL / HANNIBAL HANSCHKEHANNIBAL HANSCHKE/AFP/Getty Images

A girl looks at candles at a makeshift memorial for the attack victims, on December 20, 2016 in front of the Kaiser-Wilhelm-Gedaechtniskirche (Kaiser Wilhelm Memorial Church) in Berlin, where a truck crashed into a Christmas market. Twelve people were killed and almost 50 wounded, 18 seriously, when the lorry tore through the crowd on December 19, 2016, smashing wooden stalls and crushing victims, in scenes reminiscent of July's deadly attack in the French Riviera city of Nice. / AFP PHOTO / John MACDOUGALLJOHN MACDOUGALL/AFP/Getty Images

BERLIN, GERMANY - DECEMBER 20: German Chancellor Angela Merkel signs a book of condolences at the Kaiser Wilhelm Memorial Church the day after a truck drove into an adjacent, crowded Christmas market on December 20, 2016 in Berlin, Germany. So far 12 people are confirmed dead and 45 injured. Authorities have confirmed they believe the incident was an attack and have arrested a Pakistani man who they believe was the driver of the truck and who had fled immediately after the attack. Among the dead are a Polish man who was found on the passenger seat of the truck. Police are investigating the possibility that the truck, which belongs to a Polish trucking company, was stolen yesterday morning. (Photo by Sean Gallup/Getty Images)

TOPSHOT - German Chancellor Angela Merkel reacts before signing the book of condolences on December 20, 2016 inside the Kaiser-Wilhelm-Gedaechtniskirche (Kaiser Wilhelm Memorial Church), the day after an attack at the nearby Christmas market in central Berlin. German police said they were treating as "a probable terrorist attack" the killing of 12 people when the speeding lorry cut a bloody swath through the packed Berlin Christmas market. / AFP PHOTO / POOL / HANNIBAL HANSCHKEHANNIBAL HANSCHKE/AFP/Getty Images

TOPSHOT - Policemen patrol over the "Wiener Christkindlmarkt" Christmas market in Vienna on December 20, 2016, as security measures are taken after a deadly rampage by a lorry driver at a Berlin Christmas market. Twelve people were killed in the assault at the Berlin shopping district popular with tourists, and 48 people injured, including 18 who are severely wounded. / AFP PHOTO / APA / HERBERT PFARRHOFER / Austria OUTHERBERT PFARRHOFER/AFP/Getty Images

Candles and flowers are seen at a makeshift memorial for the attack victims, on December 20, 2016 in front of the Kaiser-Wilhelm-Gedaechtniskirche (Kaiser Wilhelm Memorial Church) in Berlin, where a truck crashed into a Christmas market. Twelve people were killed and almost 50 wounded, 18 seriously, when the lorry tore through the crowd on December 19, 2016, smashing wooden stalls and crushing victims, in scenes reminiscent of July's deadly attack in the French Riviera city of Nice. / AFP PHOTO / John MACDOUGALLJOHN MACDOUGALL/AFP/Getty Images

TOPSHOT - German Chancellor Angela Merkel (foreground), German Interior Minister Thomas de Maiziere (L) and German Foreign Minister Frank-Walter Steinmeier (2nd L) stand at a makeshift memorial for the victims of an attack on December 20, 2016 in front of the Kaiser-Wilhelm-Gedaechtniskirche (Kaiser Wilhelm Memorial Church) in Berlin, where a truck crashed into a Christmas market. Twelve people were killed and almost 50 wounded, 18 seriously, when the lorry tore through the crowd on December 19, 2016, smashing wooden stalls and crushing victims, in scenes reminiscent of July's deadly attack in the French Riviera city of Nice. / AFP PHOTO / Tobias SCHWARZTOBIAS SCHWARZ/AFP/Getty Images

A Muslim mam prays at a makeshift memorial for the attack victims, on December 20, 2016 in front of the Kaiser-Wilhelm-Gedaechtniskirche (Kaiser Wilhelm Memorial Church) in Berlin, where a truck crashed into a Christmas market. Twelve people were killed and almost 50 wounded, 18 seriously, when the lorry tore through the crowd on December 19, 2016, smashing wooden stalls and crushing victims, in scenes reminiscent of July's deadly attack in the French Riviera city of Nice. / AFP PHOTO / John MACDOUGALLJOHN MACDOUGALL/AFP/Getty Images

(L-R) Berlin's mayor Michael Mueller, German Chancellor Angela Merkel, German Interior Minister Thomas de Maiziere and German Foreign Minister Frank-Walter Steinmeier lay down flowers at a makeshift memorial for the victims of an attack on December 20, 2016 in front of the Kaiser-Wilhelm-Gedaechtniskirche (Kaiser Wilhelm Memorial Church) in Berlin, where a truck crashed into a Christmas market. Twelve people were killed and almost 50 wounded, 18 seriously, when the lorry tore through the crowd on December 19, 2016, smashing wooden stalls and crushing victims, in scenes reminiscent of July's deadly attack in the French Riviera city of Nice. / AFP PHOTO / Tobias SCHWARZTOBIAS SCHWARZ/AFP/Getty Images

A Muslim mam prays at a makeshift memorial for the attack victims, on December 20, 2016 in front of the Kaiser-Wilhelm-Gedaechtniskirche (Kaiser Wilhelm Memorial Church) in Berlin, where a truck crashed into a Christmas market. Twelve people were killed and almost 50 wounded, 18 seriously, when the lorry tore through the crowd on December 19, 2016, smashing wooden stalls and crushing victims, in scenes reminiscent of July's deadly attack in the French Riviera city of Nice. / AFP PHOTO / John MACDOUGALLJOHN MACDOUGALL/AFP/Getty Images

BERLIN, GERMANY - DECEMBER 20: German Chancellor Angela Merkel signs a book of condolences at the Kaiser Wilhelm Memorial Church the day after a truck drove into an adjacent, crowded Christmas market on December 20, 2016 in Berlin, Germany. So far 12 people are confirmed dead and 45 injured. Authorities have confirmed they believe the incident was an attack and have arrested a Pakistani man who they believe was the driver of the truck and who had fled immediately after the attack. Among the dead are a Polish man who was found on the passenger seat of the truck. Police are investigating the possibility that the truck, which belongs to a Polish trucking company, was stolen yesterday morning. (Photo by Sean Gallup/Getty Images)

German Chancellor Angela Merkel arrives to sign the book of condolences on December 20, 2016 inside the Kaiser-Wilhelm-Gedaechtniskirche (Kaiser Wilhelm Memorial Church), the day after an attack at the nearby Christmas market in central Berlin. German police said they were treating as "a probable terrorist attack" the killing of 12 people when the speeding lorry cut a bloody swath through the packed Berlin Christmas market. / AFP PHOTO / POOL / HANNIBAL HANSCHKEHANNIBAL HANSCHKE/AFP/Getty Images

A card reading in German 'In memory of the victims' is seen on December 20, 2016 at the site where a truck crashed into a Christmas market near the Kaiser-Wilhelm-Gedaechtniskirche (Kaiser Wilhelm Memorial Church) in Berlin. German police said they were treating as "a probable terrorist attack" the killing of 12 people when the speeding lorry cut a bloody swath through the packed Berlin Christmas market. / AFP PHOTO / John MACDOUGALLJOHN MACDOUGALL/AFP/Getty Images

German Chancellor Angela Merkel (L), German Interior Minister Thomas de Maiziere (2nd L) and German Foreign Minister Frank-Walter Steinmeier (3rd R) arrive to lay down flowers at a makeshift memorial for the victims of an attack on December 20, 2016 in front of the Kaiser-Wilhelm-Gedaechtniskirche (Kaiser Wilhelm Memorial Church) in Berlin, where a truck crashed into a Christmas market. Twelve people were killed and almost 50 wounded, 18 seriously, when the lorry tore through the crowd on December 19, 2016, smashing wooden stalls and crushing victims, in scenes reminiscent of July's deadly attack in the French Riviera city of Nice. / AFP PHOTO / Tobias SCHWARZTOBIAS SCHWARZ/AFP/Getty Images

(L-R) Berlin's mayor Michael Mueller, German Chancellor Angela Merkel, German Interior Minister Thomas de Maiziere and German Foreign Minister Frank-Walter Steinmeier lay down flowers at a makeshift memorial for the victims of an attack on December 20, 2016 in front of the Kaiser-Wilhelm-Gedaechtniskirche (Kaiser Wilhelm Memorial Church) in Berlin, where a truck crashed into a Christmas market. Twelve people were killed and almost 50 wounded, 18 seriously, when the lorry tore through the crowd on December 19, 2016, smashing wooden stalls and crushing victims, in scenes reminiscent of July's deadly attack in the French Riviera city of Nice. / AFP PHOTO / Tobias SCHWARZTOBIAS SCHWARZ/AFP/Getty Images

Policemen patrol over a Christmas market in Salzburg on December 20, 2016, as security measures are taken after a deadly rampage by a lorry driver at a Berlin Christmas market. / AFP PHOTO / APA / BARBARA GINDL / Austria OUTBARBARA GINDL/AFP/Getty Images

German Chancellor Angela Merkel (foreground), German Interior Minister Thomas de Maiziere (L) and German Foreign Minister Frank-Walter Steinmeier (2nd L) stand at a makeshift memorial for the victims of an attack on December 20, 2016 in front of the Kaiser-Wilhelm-Gedaechtniskirche (Kaiser Wilhelm Memorial Church) in Berlin, where a truck crashed into a Christmas market. Twelve people were killed and almost 50 wounded, 18 seriously, when the lorry tore through the crowd on December 19, 2016, smashing wooden stalls and crushing victims, in scenes reminiscent of July's deadly attack in the French Riviera city of Nice. / AFP PHOTO / Tobias SCHWARZTOBIAS SCHWARZ/AFP/Getty Images

(L-R) Berlin's mayor Michael Mueller, German Chancellor Angela Merkel, German Interior Minister Thomas de Maiziere and German Foreign Minister Frank-Walter Steinmeier lay down flowers at a makeshift memorial for the victims of an attack on December 20, 2016 in front of the Kaiser-Wilhelm-Gedaechtniskirche (Kaiser Wilhelm Memorial Church) in Berlin, where a truck crashed into a Christmas market. / AFP PHOTO / Tobias SCHWARZTOBIAS SCHWARZ/AFP/Getty Images

View of the truck that crashed into a christmas market at Gedächniskirche church in Berlin, on December 19, 2016 killing at least nine people and injuring at least 50 people. AFP/Getty Images

Medics and firefighters work at the scene where a truck crashed into a christmas market at Gedächniskirche church in Berlin, on December 19, 2016 killing at least nine people and injuring at least 50 people. AFP/Getty Images

A truck is towed away from the Christmas market at Breitscheidplatz square in Berlin, Germany, Tuesday Dec. 20, 2016. The truck ran into a crowded Christmas market in Berlin the evening before and killed several people. ( Bernd von Jutrczenka/dpa via AP)

Rescue workers gather with stretchers outside a tent in the area after a lorry truck ploughed through a Christmas market on December 19, 2016 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)

Berlin truck terrorist Anis Amri has been shot dead in Milan after attacking a police officer who asked him for ID.

Amri "immediately" produced a gun when approached by police during a routine patrol in the northern Italian city early on Friday, shooting the officer before he was gunned down.

There is "absolutely no doubt" that the man was Amri, 24, Italian interior minister Marco Minniti said.

The Tunisian was suspected of driving a truck into crowds at a Christmas market in Berlin on Monday, killing 12 people and injuring 48.

Hours after his death, Islamic State reportedly released a video showing Amri pledging allegiance to the extremist group and vowing to avenge militants killed in coalition air strikes, according to the SITE Intelligence Group.

German chancellor Angela Merkel has spoken of her relief at the death of a man she described as "one acute danger" but warned of the ongoing threat of terrorism.

Announcing Amri's death at a press conference on Friday morning, Mr Minniti said: "One of our police officers on patrol stopped a person who was just walking around looking very suspect. And the moment he was stopped, the man, without hesitating, he immediately took his gun and shot at the police officer who asked him for his identification papers."

He added: "Police officers reacted to the shootout. The person who attacked our police officer was killed.

"There is absolutely no doubt that the person who was killed is Anis Amri, the suspect of the terrorist attack in Berlin."

He said the officer who was wounded in his right shoulder during the 3am shootout, Cristian Movio, 35, is recovering in hospital.

Italian newspaper La Repubblica said Mr Movio, from Latisana, near Udine, has been in the police since 2008, adding that he also served in the army in an Alpine regiment in Venzone.

The officer who shot Amri was Luca Scata, 29, who is reportedly from Sicily and is waiting for his first official posting since qualifying for the police.

According to the Corriere della Sera website, Mr Scata's mother, who was not named in the report, said: "Being in the police has always been his dream. Luca is strong and determined and we are proud of him."

His father Giuseppe said: "He is a courageous lad, he did his duty."

Police said Amri travelled from Chambery in France to Turin in Italy, then on to Milan's Central Station where he arrived at 1am, and then on to Sesto San Giovanni.

The suspect, who turned 24 on Thursday, is understood to have left Tunisia after the 2011 Arab Spring uprising and spent time in Italy before entering Germany last year.

His asylum claim was rejected and authorities identified him as a threat before the Berlin attack.

Earlier this week, relatives of Amri urged him to turn himself in to police.

His brother, Abdelkader Amri, had previously told the Associated Press: "I ask him to turn himself in to the police. If it is proved that he is involved, we dissociate ourselves from it."

German authorities issued a wanted notice for Amri on Wednesday and offered a reward of up to 100,000 euro (£85,000) for information leading to his arrest.

Former Ukip leader Nigel Farage said Amri's apparent ability to travel from Germany to Italy showed that the Schengen system - which allows border-free movement between 26 European states - is "a risk to public safety" and should be scrapped.

"If the man shot in Milan is the Berlin killer, then the Schengen area is proven to be a risk to public safety," said Mr Farage. "It must go."