A tractor trailer barrelled into a crowded Christmas market in Berlin on Monday night, killing 12 people and injuring 48 others, a report said.

Witnesses said shoppers screamed and dropped packages and glasses of mulled wine as the truck plowed into the market, CNN reported.

Officials are investigating the crash as an act of terrorism, according to a German intelligence official familiar with the matter.

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.