A knife-wielding attacker in the German city of Mannheim on Friday targeted a gathering by the anti-Islam right-wing group Pax Europa, according to members of the group.
Police shot the attacker, who sources told dpa suffered life-threatening injuries and is awaiting a medical operation.
A policeman also suffered severe injuries and is being treated in hospital.
Pax Europa board member Michael Stürzenberger was also injured in the attack, according to the group's treasurer, Stefanie Kizina.
"He was hit in the leg and face and is undergoing emergency surgery. There is apparently no danger to life," Kizina told the Bild newspaper regarding Stürzenberger's injury.
A video apparently of the attack circulated online on Friday, showing a man stabbing several people who appeared to be participants at the Pax Europa event. He can also be seen stabbing the policeman.
People can be heard shouting "get the knife away" in the video.
The video also shows an officer shooting at the attacker. Several police officers then restrain him on the ground.
Mannheim's market square, where the incident happened, is located in the centre of the city.
Police did not immediately confirm whether the attack was on the Pax Europa gathering, but a spokeswoman for the city of Mannheim confirmed that the group had registered an event on the market square for Friday.
The square was later cordoned off with red and white police tape, screens had been erected and a nearby tram station was closed as investigators combed the area searching for evidence.
Emergency services and a rescue helicopter were deployed to treat the injured.
Many questions remain unanswered. The police were initially unable to say how many people were injured or had been taken to hospital.
A police spokesman described the injuries as "serious in some cases."
Details about the identity of the suspect or his motive for the attack also remains unclear. A police spokesman said authorities were looking into whether there was a potential political motive for the attack.
German Chancellor Olaf Scholz expressed his shock at the violence.
"The images from Mannheim are terrible. Several people have been seriously injured by an attacker," Scholz wrote in a post on X. "My thoughts are with the victims. Violence is absolutely unacceptable in our democracy. The perpetrator must be severely punished."
German Interior Minister Nancy Faeser also expressed horror at the images of the attack, and wished all the victims a speedy recovery.
"My thoughts are especially with the police officer who was seriously injured by knife wounds. I would like to thank the police officers who intervened immediately and the doctors and paramedics who are fighting for the lives of the victims of this terrible crime," Faeser said.
Mannheim's mayor, Christian Specht, said: "This brutal attack shakes and shocks us, it leaves us speechless."
Specht said his thoughts are with the injured police officer and other victims.
At the same time, he called on people not to speculate about the attacker's background or motives, but instead to wait for the results of the investigation.
Faeser, however, suggested that religious and political extremism might have motivated the attacker.
"If the investigations reveal an Islamist motive, then this would once again confirm the great danger posed by Islamist acts of violence, which we have warned about," Faeser said.
