Nine people have been killed and around 50 injured after a lorry ploughed into a crowded Christmas market in central Berlin.
According to German police, the incident bears all the marks of a deliberate attack.
The driver of the lorry has been detained, and a passenger in the lorry died at the scene, police say.
The incident is at Breitscheidplatz, near the city's main shopping street, and witnesses speak of toppled stalls and injured people lying in the street.
A huge security and rescue operation is now under way, German media says. Police are advising the general public to avoid the area and stay in their homes, the BBC reports.
Speaking to Associated Press, Mike Fox, a tourist visiting from Birmingham, said that the truck missed him by metres. "It was definitely deliberate," he told AP.
If confirmed as a terrorist attack, the incident bears a striking similarity to the 14 July truck attack in Nice, where 86 people on the city's seafront were killed by a lorry.