At least one Islamic extremist rampaged through a crowded Vienna nightlife district hours ahead of a coronavirus lockdown, leaving four people dead before he was killed by police, Austrian authorities have said.

The suspect in Monday night’s attack – a 20-year-old armed with an automatic rifle and a fake explosive vest – was identified as a young Austrian-North Macedonian dual citizen with a previous terror conviction for attempting to join the so-called Islamic State group in Syria.

Unverified video showed the suspect, dressed in white coveralls, firing off bursts apparently at random as he ran down the Austrian capital’s cobbled streets.

Police have arrested several other people and searched 15 houses and apartments, interior minister Karl Nehammer told the Austrian news agency APA.

Two men and two women died from their injuries in the attack, Chancellor Sebastian Kurz said. He added that a police officer who tried to get in the way of the attacker was shot and wounded, and another 14 people were hurt.

Vienna’s hospital service said seven people were in life-threatening condition after the attack, APA reported.

“Yesterday’s attack was clearly an Islamist terror attack,” Mr 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.”

The attacker, identified as Kujtim Fejzulai, was sentenced to 22 months in prison in April 2019 because he had tried to travel to Syria to join IS. He was granted early release in December under juvenile law.

Mr Nehammer told APA that Fejzulai had posted a photo on his Instagram account before the attack that showed him with two of the weapons he apparently used.

“(The suspect) was equipped with a fake explosive vest and an automatic rifle, a handgun and a machete to carry out this repugnant attack on innocent citizens,” Mr Nehammer said.

Authorities were still trying to determine whether further attackers are 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 the city on Tuesday morning.

The shooting began shortly after 8pm 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 8.09pm.

“We will unearth and chase down the perpetrators, those behind them and like-minded people and give them the punishment they deserve,” Mr Kurz said. “We will pursue all those who have anything to do with this outrage by all available means.”

His government on Tuesday ordered three days of official mourning, with flags on public buildings to be flown at half-mast until Thursday.

Austria held a minute’s silence at midday on Tuesday, accompanied by the tolling of bells in the capital. Mr Kurz, President Alexander Van der Bellen and other leading politicians laid wreaths and candles where the attack took place.

Fejzulai’s lawyer in the 2019 case, Nikolaus Rast, told public broadcaster ORF that his client had seemed “completely harmless” at the time.

“He was a young man who was searching for his place in society, who apparently went to the wrong mosque, ended up in the wrong circles,” Mr Rast said. “I can’t say exactly what happened.”

Fejzulai’s family “wasn’t strictly religious at all; the family wasn’t radical — it was a completely normal family”, he added. “I still remember that the family couldn’t believe what had happened with their son.”