Gdansk mayor Paweł Adamowicz has died from his injuries after he was stabbed at a charity event in Poland this weekend.
The shocking killing was witnessed by thousands of shocked spectators after the killer ran on stage and plunged a knife into his victim.
Panicked bodyguards rushed to give the 53-year-old first aid, and reports state he was given CPR before being taken to hospital for emergency surgery.
The attacker reportedly grabbed a microphone and told the crowd he had previously been wrongly imprisoned.
Leading politicians expressed shock over the incident.
Polish Prime Minister Mateusz Morawiecki wrote: "The attack on Pawel Adamowicz is worthy of the highest condemnation."
And Sadiq Khan, mayor of London, voiced his solidarity with the attack victim.
He wrote on Twitter: "Shocked to hear of the attack on Paweł Adamowicz, Mayor of Gdańsk, this evening.
"Solidarity with the city he leads, his family and supporters. We are praying for his swift recovery."