Around 30 people were also injured after a German citizen drove a van into a group of people in Muenster city, officials say, refusing to confirm local media reports that the perpetrator had psychological issues.
A man drove a van into a group of people sitting outside a popular restaurant in the old city centre of Muenster in western Germany on Saturday, killing at least two of them before shooting himself dead, police said.
The vehicle ploughed into people sitting at tables outside the Grosser Kiepenkerl restaurant, which is popular with tourists.
It was not immediately clear whether the perpetrator was among the three killed, or whether his death took the number of dead to four. A police spokeswoman said separately that there were at least three people dead.
"The driver shot himself," the spokeswoman said, adding that around 30 people were injured in the incident.
North Rhine-Westphalian interior minister said the van attack suspect was German.
"According to the current state of the investigation, and it is really still early, the perpetrator who after 3 pm (local time) ploughed into a crowd of people, was a German citizen and not as it was everywhere alleged a refugee or something similar," Herbert Reul said.
"The details are being thoroughly examined. Because of that it can't now be said what was the background. There is nothing saying at the moment that there was any Islamist background, but it must be waited on. It will be investigated from all sides."
Investigators were also looking at the possibility that other suspects fled the scene, though they had no evidence this was the case, police said.
Police also urged people to refrain from spreading "speculation" and "rumours" about the incident.
#Kiepenkerl #Münster Bitte unterlasst die Spekulationen und Gerüchte. Wir sind vor Ort und ermitteln zum Tathergang. Sobald wir mehr gesicherte Informationen haben werden wir Euch hier dazu informieren.— Polizei NRW MS (@Polizei_nrw_ms) April 7, 2018
Motive of the attack not clear
It was not immediately clear whether the perpetrator was among the three killed, or whether his death took the number of dead to four.
A security source said the perpetrator was probably German.
The Sueddeutsche Zeitung newspaper reported the man was a German with psychological problems who had no terrorist background.
Public broadcaster ZDF said the man had recently attempted suicide.
Police spokesman Peter Nuessmeyer told Associated Press that he could not confirm German media reports that the perpetrator reportedly had psychological issues.
"There was a bang and then screaming. The police arrived and got everyone out of here," an employee of one the cafes hardest hit by the rampage told rolling news channels N24 and NTV.
"There were a lot of people screaming. I'm angry - it's cowardly to do something like this."
Police operation underway
Images broadcast by German television showed several police and firefighting vehicles clustered around a street in the centre of the picturesque medieval city of 300,000 people.
Muenstersche Zeitung reported on its website that the VW Bulli used in the incident was packed with explosives.
According to the local newspaper, experts were on scene neutralising the explosives.
It said police responded quickly to the incident and in numbers as they had been on duty for a nearby political protest.
The incident evoked memories of a December 2016 truck attack in Berlin that killed 12 people.
Anis Amri, a failed Tunisian asylum seeker with extremist links, hijacked a truck on December 19, 2016, killed the driver and then ploughed it into a crowded marketplace, killing 11 more people and injuring dozens of others.