One person died in the city centre incident involving a small Renault car, Germany's Bild newspaper reported.

A man believed to be the driver of the vehicle has been detained, Berlin police said.

It is unclear whether the incident was the result of an accident or whether the driver had intentionally driven into the crowd, Berlin police spokesman Martin Dams said.

It took place on Rankestrasse near the main shopping district's Breitscheidplatz, the scene of the 2016 Christmas market attack in which 11 people were killed.

"We think we have witnessed a terrorist attack here in Berlin," tweeted actor John Barrowman from the scene.

"We're not sure there's a lot of people dead bodies all over the place.

"We've seen a car that came down the road and ended up in a storefront covering three city blocks.

"It's pretty horrific."