According to emergency services, a vehicle crashed into a crowd in west Berlin and injured about 30 people.
One person was killed in a downtown incident with a small Renault car, the German newspaper Bild reported.
A man believed to be the driver of the vehicle has been arrested, Berlin police said.
Image: Emergency services said about 30 people were injured. Image: John Barrowman / Scott Gill
It is unclear whether the incident was the result of an accident or whether the driver had intentionally entered the crowd, said Berlin police spokesman Martin Dams.
It took place in Rankestrasse, near the Breitscheidplatz in the main shopping district, the scene of the 2016 Christmas market bombing in which 11 people were killed.
“We believe we witnessed a terrorist attack here in Berlin,” actor John Barrowman tweeted from the scene.
“We are not sure if there are a lot of corpses everywhere.
“We saw a car go down the road and end up in a shop on three blocks from the city.
“It’s pretty awful.”