A big rig cruising at 40 mph plowed into a crowded Christmas market in Berlin Monday night, killing at least 12 people in a suspected terrorist attack.

The crash happened in Breit­scheidplatz square in the western part of the German capital at around 8 p.m. and left nearly 50 people injured.

The driver of the Scania truck was apprehended but has yet to be identified. He is believed to be a Pakistani refugee who arrived in Germany in February, according to local reports.

A passenger — who was said to be riding in the cab at the time of the crash — was found dead after the suspected attack, though it’s unclear how he died. Berlin police later confirmed on Twitter that he was a Polish citizen.

“A man who was apparently driving the truck was detained,” a police spokeswoman told AFP. “The person riding in the vehicle is dead.”

Berlin police said early Tuesday that the attack was done on purpose. Police officials said that the truck used in the crash appeared to have been stolen or hijacked. It had Polish license plates and belonged to a Polish delivery company, The Guardian reports.

The company later told the AFP that their 37-year-old driver was missing — and that he had been transporting Thyssen steel products from Italy to Berlin at the time.

It is unclear whether the man who was found dead in the cab of the truck was the driver.

The incident was similar to the Bastille Day terror attack in Nice, France, on July 14, in which a French-Tunisian national plowed a cargo truck into a crowd of holiday revelers, killing 86 and injuring more than 400.

ISIS claimed responsibility for that horror.

One witness told CNN that the 18-wheeler was going about 40 mph when it hopped the curb and careened through a group of stalls in Breitscheidplatz – a major shopping area — with no signs of stopping.

“It was the first day in Berlin for me we went down to the Christmas market and were enjoying the Christmas lights and some mulled wine and as we sat we were ready to get up and we heard a loud bang,” recalled Emma Rushton, who was just feet away from the truck when it crashed into the market.

“Then we started to see to our left that the Christmas lights were being torn down and we started to see the top of an articulated truck, a lorry, just crushing through the stores and through people,” she said.

The driver accelerated for quite some time — traveling between 50 and 80 yards — before finally coming to a halt, according to police.

When asked whether the crash appeared to be accidental, Rushton told CNN there was no way.

“There were no roads nearby and there were no signs of slowing down,” she said. “It didn’t look or feel like it was an accident…There’s no way it could have just come off [the road] as an accident. It went through the middle of the market.”

Video posted to Twitter by Berliner Morgenpost reporter Daniel Nisman showed the giant, all black semi and the some of the destruction it left in its wake.

“The store where we bought the mulled wine from as completely decimated,” Rushton told CNN. “Everybody who was inside serving was crushed underneath it.”

After crashing the truck, the driver fled the scene — darting off toward Berlin’s central park, known as the Tiergarten, where he was eventually captured.

German police officials tweeted that there were currently no threats of further attacks in Berlin.

The suspected attack comes less than a month after the US state department issued a travel warning for US citizens visiting Europe, noting how they had obtained “credible information” of possible terror strikes at Christmas and holiday events, such as crowded markets.

Officials warned that ISIS and al-Qaeda had been planning attacks for months, with a specific focus on the holiday season. The travel advisory is set to continue until Feb. 20.

The White House called the incident an apparent terror attack.

“The United States condemns in the strongest terms what appears to have been a terrorist attack on a Christmas Market in Berlin, Germany, which has killed and wounded dozens,” wrote National Security Council spokesperson Ned Price. “We send our thoughts and prayers to the families and loved ones of those killed, just as we wish a speedy recovery to all of those wounded. We also extend our heartfelt condolences to the people and Government of Germany. We have been in touch with German officials, and we stand ready to provide assistance as they recover from and investigate this horrific incident. Germany is one of our closest partners and strongest allies, and we stand together with Berlin in the fight against all those who target our way of life and threaten our societies.”

The NYPD also released a statement on Monday night, expressing their condolences, as well.

“Our prayers go out to the families of those who lost their lives today in Berlin, those injured, and all who are affected by this tragedy,” the department tweeted.

While police did not officially identify a suspect or declare a motive, President-elect Donald Trump blamed the incident on “Islamist terrorists,” saying they targeted “innocent” Christians as they “prepared to celebrate the Christmas holiday.”

“Our hearts and prayers are with the loved ones of the victims of today’s horrifying terror attack in Berlin,” he said in a statement Monday night.

“Innocent civilians were murdered in the streets as they prepared to celebrate the Christmas holiday. ISIS and other Islamist terrorists continually slaughter Christians in their communities and places of worship as part of their global jihad.

“These terrorists and their regional and worldwide networks must be eradicated from the face of the earth, a mission we will carry out with all freedom-loving partners.”

Trump also fired off a tweet in which he hinted at taking a stand against global terrorism.

“Today there were terror attacks in Turkey, Switzerland and Germany — and it is only getting worse. The civilized world must change thinking!” he said.

The crash is just the latest in a long line of deadly attacks to have taken place in Germany over the past year.

On July 24, a Syrian suicide bomber targeted a music festival in Ansbach — injuring 15 people.

Just days earlier, an 18-year-old man with dual German and Iranian nationality gunned down nine people in Munich, though his motives were unclear.

Less than a week before that incident, an ISIS-inspired Afghan refugee stabbed five passengers on a train in Bavaria. The teen, who was armed with a knife and an ax, was eventually killed by police.

In May, a German man knifed four people at another train station in Bavaria, killing one person and injuring three others. He allegedly shouted “Allahu akbar” and “infidels must die” as the attack unfolded.

With Post wires