Updated at 12:35 p.m. ET
The mayor of the Polish city of Gdansk, Pawel Adamowicz, has died a day after he was stabbed in the heart and abdomen at a charity event attended by thousands of people.
Adamowicz, 53, was onstage after speaking at Sunday's finale of the annual Great Orchestra of Christmas Charity event, which raises money for medical equipment to treat sick children. TV footage showed Adamowicz telling the audience it had been a "wonderful day" just before he was attacked, The Associated Press reports.
The assailant ran onto the stage with a knife and stabbed Adamowicz, who the AP says grabbed his stomach and collapsed. The mayor was rushed to a hospital and underwent five hours of surgery before he succumbed to his wounds.
The attacker turned to the crowd after the stabbing and said he had been wrongly imprisoned under a previous national government that Adamowicz had belonged to, the AP said. "I was jailed but innocent," the suspect said. "Civic Platform tortured me. That's why Adamowicz just died."
Police arrested the suspect, a 27-year-old man they identified only as Stefan. Reuters reports the man was "released last month from prison where he had been serving a 5 1/2 year sentence since 2014 for attempting to steal from banks in Gdansk."
The head of the Great Orchestra of Christmas Charity, Jerzy Owsiak, resigned his position Monday. Owsiak told reporters he had received threats and hate messages for years but got no help from police, the AP reports. Owsiak said in a statement provided in English that his country was "famous for re-inventing freedom" but "got so confused in the last three years."
"To think that this act of violence took place in my hometown ... I am shaken," Owsiak wrote.
Adamowicz had served as mayor of Gdansk since 1998. The attack on him spurred an outpouring of support: Hundreds of people had lined up to donate blood while the mayor struggled for his life, according to Polish media. The nearby city of Lodz announced it would open additional blood donation centers. "We call on Lodz citizens to donate blood," the city's Deputy Mayor Adam Wieczorek said. "Let the blood flow from Lodz to Gdansk."
The Gdansk city flag was lowered to half-staff, the AP reports. Marches against violence were being planned across Poland on Monday night.
Adamowicz organized student strikes for the Solidarity movement that helped end Communism in eastern Europe. He clashed with Poland's populist government in recent years. Adamowicz was a vocal supporter of LGBT rights and refugees and lamented the direction Poland has taken under its current right-wing leadership. In a 2016 interview with NPR, he said, "And for our Democrats like me – liberals — it's a challenge how to mobilize people for our constitution and our values."
The mayor pushed to bring wounded Syrian children to his city for medical treatment, the AP reports. The plan was blocked by the ruling Law and Justice government. A far-right group issued what they called a "political death notice" for the mayor after he pushed for his plan.
Polish President Andrzej Duda of the Law and Justice Party extended condolences Monday to Adamowicz's family.
Immediately after the attack, Duda nodded to the divide between his party and the slain mayor on Twitter. "We usually differ" on how Polish affairs should be carried out, Duda wrote. "But today I am unconditionally with him and his dear ones."
Tributes came from around the world.
U.S. Ambassador to Poland Georgette Mosbacher called the killing an "unimaginable tragedy."
Donald Tusk, president of the European Council, wrote, "Pawel Adamowicz, Mayor of Gdansk, a man of Solidarity and freedom, a European, my good friend, has been murdered. May he rest in peace."