Several people were wounded in a knife attack in the German city of Mannheim on Friday, police said, with Chancellor Olaf Scholz decrying the "terrible" incident.

A man with a knife attacked and injured several people on the market square in Mannheim at around 11.35 am, police said in a statement.

Police then shot at the attacker, who was also injured as a result.

German media reported that one of the victims of the assault, which took place just days before EU-wide elections, was a prominent Islam critic.

"The extent and severity of the injuries are not yet known," the police said, adding that there was no further danger to the public.

"The images from Mannheim are terrible," Scholz wrote on X, formerly Twitter.

"Violence is absolutely unacceptable in our democracy. The perpetrator must be severely punished."

According to several media reports, one of the victims was Michael Stuerzenberger, a German far-right activist and blogger.

Stuerzenberger had been due to speak at a rally in Mannheim on Friday organised by Pax Europa, a campaign group against radical Islam.

The group said on its website that Stuerzenberger and several Pax Europa volunteers were injured in a knife attack at the rally.

Stuerzenberger suffered serious stab wounds to his face and also to his leg, while a police officer was also stabbed in the back and neck, the group said.

Stuerzenberger has been a prominent anti-Islam campaigner in Germany for several years.

Pax Europa has been classed as Islamophobic by Bavarian security services, which have also accused Stuerzenberger of making "Islamophobic statements".

Germany has seen a spate of attacks on politicians at work or on the campaign trail in the run-up to the EU elections on June 9.

President Frank-Walter Steinmeier last week said he was worried by the growing trend and Germans "must never get used to violence in the battle of political opinions".