The mayor of the northern Polish city of Gdansk has been stabbed while on stage at a major charity event, officials say.
Pawel Adamowicz, 53, is reportedly in a critical condition in hospital.
The suspect, a 27-year-old local resident, had access to the scene using a media badge, Polish media report. He has been detained.
Interior Minister Joachim Brudzinski said the attack was “an act of inexplicable barbarism”.
The incident took place at the Great Orchestra of Christmas Charity event which was attended by hundreds of people.
The suspect reportedly shouted that he had been wrongfully imprisoned.
Prime Minister Mateusz Morawiecki said on Twitter: “The attack on life and health of Paul Adamowicz is worthy of the highest condemnation.”
Also on Twitter, President Andrzej Duda said: “I pray for his return to health and full strength.“