German police said they shot and wounded a man armed with a knife who attacked a right-wing demonstration in the southwestern city of Mannheim on Friday.
Social media footage showed a bearded man in glasses attacking people in the city's central Marktplatz square with a knife. One person appears to be stabbed in the leg and a policeman who tries to intervene appears to be cut in the neck. Another policeman then shoots the attacker.
"A firearm was used against the attacker," Mannheim police said in a statement.
No information was available on the identity or motives of the attacker and police said they could not yet give details about any injuries among the demonstrators in the square.
A livestream broadcast from central Mannheim showed anti-Islam activist Michael Stuerzenberger preparing to address a small crowd at an event put on by the anti-Islam Pax Europa Movement.
The footage bore a watermark linked to the movement's "Open Eyes" tour.
A colleague of Stuerzenberger told Bild newspaper the activist had been stabbed in the face and leg.
The injured policeman had undergone an emergency operation, Bild reported.
The violence comes in the final stretch of a European parliament campaign in which the far-right Alternative for Germany party has campaigned partially on what the party says is the danger posed by migration from Muslim countries.
"If investigations show an Islamist motive behind the attack, that would be yet another confirmation of the great danger posed by Islamist violence, which we have been warning about," Interior Minister Nancy Faeser said in a statement.
"The attacker must be punished severely," added Chancellor Olaf Scholz on X.
Stuerzenberger, 59, who describes himself as an Islam-critical journalist, has been a member of several far-right anti-Islam organisations, including the PEGIDA movement that holds regular marches in cities especially in eastern Germany.