The mayor of the Polish city of Gdansk has died in hospital a day after being stabbed at a charity event.
Pawel Adamowicz, 53, was attacked on stage in front of hundreds of people on Sunday.
He was hospitalised for serious abdominal injuries and underwent five hours of surgery.
A 27-year-old with a criminal record has been arrested over the attack. Police believe he used a media pass to gain access to the stage.
Local television footage showed the suspect, who was recently released from prison, brandishing a weapon and shouting.
He reportedly said "Adamowicz is dead" and that the Civic Platform party, which led the previous government and had supported Mr Adamowicz's re-election, had wrongfully imprisoned him.
Poland's health minister on Monday confirmed Mr Adamowicz had died from his injuries.
The mayor was attacked while attending the Great Orchestra of Christmas charity - an annual event where volunteers raise money for medical equipment in hospitals.
Moments before he was stabbed, Mr Adamowicz had posted a picture from the stage on Instagram.
The mayor was known for his liberal views and opposition to Poland's ruling Law and Justice (PiS) party.
After news of the severity of his condition broke, local residents queued at the hospital to donate blood.
In a tweet on Monday, Prime Minister Mateusz Morawiecki described Mr Adamowicz's murder as a "huge tragedy" for the country.
Anti-violence rallies are being planned across Poland in response to the attack.