Warsaw, Poland — Polish blood donors rushed forward in droves on Monday in a bid to save the life of Gdansk's mayor, who was stabbed in the heart and abdomen while on stage at a charity event, but Pawel Adamowicz died hours later of his injuries. Doctors operated for five hours on Adamowicz, who was stabbed on Sunday by an ex-convict who rushed onto the stage with a knife.

Poland's health minister Lukasz Szumowski confirmed that the mayor had died of his injuries, saying later on Monday, "we couldn't win."

Polish Justice Minister Zbigniew Ziobro said prosecutors were looking closely at the trial five years ago of the man accused of stabbing Adamowicz. The suspect was convicted of involvement in bank robberies and served the 5½-year prison term in full.

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Ziobro, who is also the country's chief prosecutor, said Monday the term was not very high given the crime, and noted the man was refused parole three times. Ziobro, a prominent figure in the right-wing government, said he found no words to describe the "evil" of this "terrible event."

Adamowicz grabbed his belly and collapsed in front of the audience at the 27th annual fundraiser organized by the Great Orchestra of Christmas Charity.

One of the surgeons, Dr. Tomasz Stefaniak, had said earlier that Adamowicz was in "very, very serious condition" after he suffered a "serious wound to the heart, a wound to the diaphragm and to the internal organs." He said Adamowicz needed massive blood transfusions.

Gdansk Mayor Pawel Adamowicz speaks on Jan. 13, 2019. Agencja Gazeta/Bartosz Banka via REUTERS

Private TVN24 showed people standing in line and then donating blood in Gdansk on Monday. Some said they were given time off work to help save Adamowicz. A rally against violence was also planned.

Gdansk Archbishop Leszek Slawoj Glodz, who was at the hospital during the surgery, said he was praying for a "miracle."

After the knife attack, the assailant shouted from the stage that he had been wrongly imprisoned under a previous national government led by Civic Platform, a party to which the mayor formerly belonged. He said his name was Stefan and that "I was jailed but innocent. ... Civic Platform tortured me. That's why Adamowicz just died."

A police spokesman, Mariusz Ciarka, said the attacker appeared to have mental problems and gained access to the area with a media badge. It was unclear how he acquired the credential.

He was arrested and is under investigation.

TVN footage showed Adamowicz on stage with a sparkler in hand telling the audience that it had been a "wonderful day" and then the attacker coming toward him. The mayor had been on the streets of his Baltic port city earlier in the day collecting money for the nationwide charity that supports Poland's financially-strapped hospitals.

European Council President Donald Tusk, a former Polish prime minister who co-founded Civil Platform and is from Gdansk, tweeted: "Let's all pray for Mayor Adamowicz. Pawel, we are with you."

The head of the charity, Jerzy Owsiak, is a liberal critic of Poland's current right-wing government. Owsiak and some opposition politicians blamed what they described as an atmosphere of hate under the ruling Law and Justice party for the attack on the mayor.

Owsiak referred to being personally depicted in a defamatory manner in an animation that ran on state TV last week and also had anti-Semitic overtones. The animation showed Owsiak as a clay figure being manipulated by a leading Civic Platform official who seized piles of cash he collected. A Star of David was on one of the banknotes. The broadcaster apologized after the animation triggered an outcry.

Adamowicz, 53, was part of the democratic opposition formed in Gdansk under the leadership of Lech Walesa during the 1980s. After leaving Civic Platform, he was re-elected to a sixth term as an independent candidate in the fall.

As mayor, he has been a progressive voice, supporting LGBT rights and tolerance for minorities. He marched in last year's gay pride parade, a rare action for a mayor in Poland.

He also showed solidarity with the Jewish community when the city's synagogue had its windows broken last year, strongly denouncing the vandalism.

The stabbing shocked the nation Sunday. Moments before the attack, Adamowicz posted an image of the stage on Instagram, BBC News reports.

"Horrified by the brutal attack on Gdansk mayor Pawel Adamowicz," tweeted Frans Timmermans, a Dutch politician and leading European Union official. "Hope and pray he will recover. A great leader of his city and a true humanitarian."

The last attack on a politician in Poland was in 2010 in Lodz. A man shouting that he wanted to kill Law and Justice party leader Jaroslaw Kaczynski fatally shot an aide to one of the party's lawmakers to the European Parliament. A second man was stabbed and injured.

At the time, Law and Justice was in the opposition and Kaczynski blamed the attack on an "atmosphere of hate" under rival party Civic Platform.