Updated

The Islamic State claimed responsibility for a shooting Monday in the heart of Vienna that killed five people, including an assailant, and wounded 17 others hours before a coronavirus lockdown, Austrian authorities said Tuesday.

The dead attacker was a 20-year-old Austrian-North Macedonian dual national who had a previous terror conviction. The terror group posted a video online of the alleged perpetrator, named as Kujtim Fejzulai, pleading allegiance to ISIS. 

Two men and two women died from their injuries in the attack Monday evening, Chancellor Sebastian Kurz said. The suspected attacker was shot and killed by police.

Vienna’s hospital service said seven people were in life-threatening condition Tuesday after the attack, the Austrian news agency APA reported. In total, 17 people were being treated in hospitals, with gunshot wounds but also cuts.

“It is now confirmed that yesterday's attack was clearly an Islamist terror attack," Kurz said. “It was an attack out of hatred — hatred for our fundamental values, hatred for our way of life, hatred for our democracy in which all people have equal rights and dignity.”

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Interior Minister Karl Nehammer later told APA that the dead assailant, who had roots in the Balkan nation of North Macedonia, had a previous conviction under a law that punishes membership in terrorist organizations.

Fejzulai was sentenced to 22 months in prison in April 2019 because he had tried to travel to Syria to join ISIS. He was granted early release in December under juvenile law.

Fifteen house searches have taken place and several people have been arrested, Nehammer said. The attacker, he said, "was equipped with a fake explosive vest and and an automatic rifle, a handgun and a machete to carry out this repugnant attack on innocent citizens.”

Police officers walk at the scene after gunshots were heard, in Vienna, Nov. 2. Austrian police say several people have been injured and officers are out in force following gunfire in the capital Vienna. Initial reports that a synagogue was the target of an attack couldn't immediately be confirmed. Austrian news agency APA quoted the country's Interior Ministry saying one attacker has been killed and another could be on the run.(Photo/Ronald Zak)

Police officers walk at the scene after gunshots were heard, in Vienna, Nov. 2. Austrian police say several people have been injured and officers are out in force following gunfire in the capital Vienna. Initial reports that a synagogue was the target of an attack couldn't immediately be confirmed. Austrian news agency APA quoted the country's Interior Ministry saying one attacker has been killed and another could be on the run.(Photo/Ronald Zak)

Authorities were still trying to determine whether further attackers may be on the run. People in Vienna were urged to stay at home if possible on Tuesday and children did not have to go to school. Some 1,000 police officers were on duty in Vienna on Tuesday morning.

Among those wounded in the attack was a police officer, said Nehammer. The 28-year-old officer was in the hospital but no longer in a life-threatening condition.

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The shooting began shortly after 8 p.m. Monday near Vienna’s main synagogue as many people were enjoying a last night of open restaurants and bars before a month-long coronavirus lockdown, which started at midnight.

Vienna police chief Gerhard Puerstl said the attacker was killed at 8:09 p.m.

Chancellor Sebastian Kurz said that “we are victims of a despicable terror attack in the federal capital.”

His government on Tuesday ordered three days of official mourning, with flags on public buildings to be flown at half-staff until Thursday, APA reported. A minute of silence was to be held at noon Tuesday.

Unverified footage posted on social media showed a gunman walking through the streets, apparently shooting at people at random, wounding several. It was unclear whether the person seen shooting was the same individual in each video.

Rabbi Schlomo Hofmeister said he saw at least one person shoot at people sitting outside at bars in the street below his window near the city’s main synagogue.

“They were shooting at least 100 rounds just outside our building,” Hofmeister said. “All these bars have tables outside. This evening is the last evening before the lockdown.”

Authorities said residents have uploaded 20,000 videos of the attack to police.

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The attack drew swift condemnation and assurances of support from leaders around Europe, including from French President Emmanuel Macron, whose country has experienced three Islamist attacks in recent weeks, and German Chancellor Angela Merkel.

“The Islamist terror is our common enemy,” Merkel spokesman Steffen Seibert tweeted. “The battle against these murderers and their instigators is our common fight.”

As a precautionary measure, the United Kingdom raised its national security threat level to severe Tuesday, meaning the likelihood of an attack is high. 

President Donald Trump tweeted Monday night as he prepared for his final rally ahead of Election Day: “Our prayers are with the people of Vienna after yet another vile act of terrorism in Europe.”

“These evil attacks against innocent people must stop,” Trump added. “The U.S. stands with Austria, France, and all of Europe in the fight against terrorists, including radical Islamic terrorists.”

Egypt’s Al-Azhar, the Sunni Muslim world’s foremost religious institution, condemned the “terrorist attacks” in Vienna. It called on international institutions “to stand united” against terrorism and reject violence and hatred.

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Austria’s military has provided 75 soldiers to guard key sites in Vienna, freeing up police to continue the investigation.