A truck plowed into a crowd at a Christmas market in the German capital Berlin on Monday evening, killing at least 12 people and injuring at least 48 others, the police said.

Police said a suspect believed to be the driver was arrested nearby and a passenger was dead. Germany's interior minister told the press that he doesn't want to speculate, but "a lot points to an attack."

>> Be the first to get updates on Berlin: Download our App, sign up to Breaking News Alerts, and Subscribe

The suspect likely came to Germany as a refugee in February and was either from Afghanistan or Pakistan, a security source has told dpa. The man had used different names, which was making his identification more difficult, the source added.

Berlin police said on Tuesday that investigators assume that the driver of the truck that crashed into the capital's popular Christmas market at the Kaiser Wilhelm Memorial Church did so intentionally.

Open gallery view Police and emergency workers at the site of a truck plowing at a Christmas market in Berlin, Germany, December 19, 2016. Credit: Fabrizio Bensch, Reuters

"Our investigators assume that the truck was deliberately steered into the crowd at the Christmas market at Breitscheidplatz," police said on Twitter.

They also said that a man found dead in the truck was not controlling it.

Germany's justice minister said that federal prosecutors, who handle terrorism cases, were taking over the investigation.

The truck, which was loaded with steel beams, came to a halt on a sidewalk on one side of the market. It had just rammed a large stand called "Fascination Christmas," tearing off one side and knocking down a large Christmas tree. The three-meter tree lay in the street, red and gold ornamental balls still attached to its limbs and a golden star at the top.

Open gallery view Police and emergency workers at the site of a truck plowing at a Christmas market in Berlin, Germany, December 19, 2016. Credit: Fabrizio Bensch, Reuters

The Polish owner of the truck told media that the driver, who was driving the truck from Gdansk to Berlin, was his cousin. Ariel Zurawki added that he doesn't believe it was his cousin who carried out the attack, and said it's possible that the truck was hijacked. He added that he has been unable to contact his cousin.

The crash came less than a month after a U.S. State Department calling for caution in markets and other public places, saying extremist groups including Islamic State and al-Qaida were focusing "on the upcoming holiday season and associated events."

Islamic State and al-Qaida have both called on followers to use trucks in particular to attack public places. On July 14, a truck plowed into a Bastille Day crowd in the southern French city of Nice, killing 86 people. Islamic State claimed responsibility for that attack, which was carried out by a Tunisian living in France.

U.S. President-elect Donald Trump condemned the Berlin "attack," saying in a statement that ISIS and other "Islamic terrorists" were slaughtering Christians as "part of their global jihad."

On Twitter, Trump added: "Today there were terror attacks in Turkey, Switzerland and Germany - and it is only getting worse. The civilized world must change thinking!"

Open gallery view Firefighters look at a toppled Christmas tree after a truck ran into a crowded Christmas market and killed several people in Berlin, Germany, Monday, Dec. 19, 2016. Credit: Michael Sohn/AP

Trump earlier termed the assassination of the Russian envoy in Turkey as the act of an "radical Islamist terrorist." Also on Monday, an unknown gunman opened fire in a mosque in Zurich. Swiss authorities weren't considering the attack as terrorism, police said. It was not immediately clear if that was the event Trump was referring to.

Television pictures from Berlin showed the truck standing amid debris by small wooden stalls that make up the "Christkindlmarkt" of which there are several in Berlin at this time of year.

Mike Fox, a tourist from Birmingham, England, told The Associated Press at the scene in Berlin that the large truck missed him by about three meters as it drove into the market, tearing through tables and wooden stands.

"It was definitely deliberate," Fox said. Fox said he helped people who appeared to have broken limbs, and that others were trapped under Christmas stands.

Federal prosecutors, who handle terrorism cases, took over the investigation, according to German Justice Minister Heiko Maas, who said in a tweet "we are mourning with the relatives" of the victims. Interior Minister Thomas de Maiziere gave no indication in a statement whether authorities believe the crash was an attack.

Dozens of ambulances lined the streets waiting to evacuate people, and heavily armed police patrolled the area. Police on Twitter urged people to stay away from the area, saying they need to keep the streets clear for the rescue vehicles.