Three people have been killed and 20 injured after a van ploughed into a crowd in the western German city of Muenster.
The vehicle crashed into people sitting in front of the famous Kiepenkerl bar in the historic downtown area on Saturday afternoon.
Shocking images posted on social media show a silver van among scattered tables and chairs in a cobbled square.
Others show a massive police presence as emergency services descended on the scene and a large area was sealed off.
A police spokesman said six people have suffered serious injuries.
Andreas Bode added that the driver of the van shot himself inside the car after the crash but, according to news agencies, German police are checking reports that other perpetrators may have fled from the van.
Police are checking witness reports that others left the van after it crashed outside the popular bar and German news agency dpa reported that witnesses spoke of two others in the van besides the driver.
Officers have urged people in Muenster to stay inside their homes and avoid the crash scene in the city’s historic downtown.
The city centre remained closed following the incident, as police secured the area and worked to establish if there were any suspicious items in the vehicle.
A object was found in the van, police said, and is being examined by officers. It is not yet clear if it is dangerous.
Daniel Kollenberg, who lives in the city, said he was “shocked” by the incident.
He told the BBC Muenster was “completely under lockdown”. He said there was a “heavy police presence” and “two police helicopters are in the air”.
Local police tweeted earlier: “There are dead and injured. Please avoid the area. More information can be found here. We are on site.”
Authorities said it was too early to speculate about the motive behind the crash, adding an investigation is underway.
A security source added: “The scenario is such that an attack cannot be ruled out.”
Residents were told “avoid the area near the Kiepenkerl pub” while a large-scale police operation got underway.
The suspicious object in the van is understood to be the reason why a large area around the scene was cordoned off after the crash.
A spokeswoman for German Chancellor Angela Merkel said “our thoughts are with the victims and their families”.
Ulrike Demmer added on Twitter that the crash was “terrible news”.
Exactly a year ago an attacker reported to be an Isis-sympathiser killed four people when he drove a truck into crowds in a busy street in Stockholm.
And a man killed 12 when he drove a lorry into a Christmas market in the German capital, Berlin, in December 2016.
Muenster is a city 300 miles west of Berlin.