Officials are investigating the crash as an act of terrorism, according to a German intelligence official familiar with the matter.
After a tip, Berlin police arrested a man on foot about a mile and a half away from the crash site. Authorities are working to determine whether he is linked to the case.
Some of the 48 people in the hospital have serious injuries, Berlin police tweeted.
The truck that was involved in the crash at Breitscheidplatz, in the western part of central Berlin, had Polish license plates, police spokeswoman Kerstin Ziesmer said. Berlin police tweeted that a passenger found dead in the truck was a Polish citizen.
Ariel Zurawski, owner of the truck company, told TVN 24, a private Polish television news network and CNN affiliate, the truck, carrying a steel shipment, may have been hijacked.
Zurawski said his cousin — the truck’s regular driver — couldn’t have been behind the wheel.
“My scenario is that they did something to him and hijacked this truck,” he said.
Witness Emma Rushton told CNN that the truck didn’t slow down. She said the truck was traveling about 40 mph through the crowded pedestrian area.
“There’s no way it was an accident,” Rushton said. “We saw at least 10 people” injured and lying on the ground.
German officials have been concerned about security around Christmas markets, which are the main place for holiday shopping and refreshments, such as the mulled beverage Gluhwein.
The US State Department alerted US citizens in November to the heightened risk of terrorist attacks throughout Europe, especially during the holiday season. The alert, which encouraged citizens to be cautious at the holiday festivals, expires on February 20.
Reichelt told CNN that the market would be busy every night of the week leading up to Christmas. The market at Kaiser Wilhelm Memorial Church has existed for 33 years, according to the Visit Berlin website
. The stands offer delights such as handmade crafts, “sweet waffles, candied fruit and nuts crafts.”