The Austrian capital of Vienna has been left reeling after a gunman killed multiple civilians and injured several others in the city center on Monday evening in what Chancellor Sebastian Kurz described as a "repulsive terror attack."

The attacks carried out at several locations in Vienna, including near a synagogue, have left two men and two woman dead. Around 22 more people were injured, including a police officer, while three of the victims remain in critical condition, according to the city's mayor. 

One of the people killed was the Chinese-Austrian owner of an Asian noodle restaurant near the synagogue and one of those injured was a Chinese bakery worker, according to China's Embassy in Vienna. In a statement on its WeChat account the embassy said it had contacted the injured person and other relevant parties and would closely follow the development of the situation and provide necessary consular assistance. 

A gunman identified as a sympathiser of the so-called Islamic State (ISIL), was shot dead by police. Fourteen suspects have been arrested so far and Austrian police have raided 18 premises.

Authorities had previously said they could not rule out the possibility that other shooters were still on the loose and asked people to avoid the center of Vienna, which was largely deserted on Tuesday with most shops closed.

Interior Minister Karl Nehammer said footage of the incident filmed on mobile phones showed no evidence of a second gunman, although the possibility had not been completely ruled out.

As a large-scale police operation continues, here's what we know so far.

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FACTSHEET

- Four civilians killed in gun attack on evening diners and drinkers in Vienna

- Gunman killed by police had been jailed for planning to join ISIL

- Chancellor Kurz describes 'fight between civilisation and barbarism'

- Police search 18 properties in wide-scale manhunt

- Fourteen people arrested, two in the Austrian city of St. Poelten and another in Linz

Monday's attack

The first shots were heard in Vienna's city center at around 8 p.m. local time, just hours before Austria was to reimpose a coronavirus lockdown, with people out in bars and restaurants for a final night out.

Attacks took place at the six different locations, the first taking place near the city's main synagogue. One witness told public broadcaster ORF: "It sounded like firecrackers, then we realized it was shots." 

A gunman "shot wildly with an automatic weapon" before police arrived and opened fire, the witness added. Another bystander said at least 50 shots were fired.

In a televised press conference, Kurz said the victims were an elderly man and woman, a young passerby and a waitress and pledged to "hunt down the perpetrators and those who stand behind them."

Earlier, Kurz told ORF the attacker(s) "were very well equipped with automatic weapons" and had "prepared professionally."

Videos circulated on social media of a gunman running down a cobblestone street shooting and shouting. One showed a man gunning down a person outside what appeared to be a bar on the street housing the synagogue, which was closed at the time of the attack.

Oskar Deutsch, the head of Vienna's Jewish community, which has offices adjoining the synagogue, said on Twitter that it was not clear whether the temple or offices were targeted.

Police sealed off much of the historic center of the city overnight, urging the public to shelter in place. During the attack many sought refuge in bars and hotels, while public transport throughout the old town was shut down as police searched the city.

"The attack yesterday was clearly an Islamic terror attack," Kurz stated. "This is not a conflict between Christians and Muslims or between Austrians and migrants. No, this is a fight between the many people who believe in peace and the few [who oppose it]. It is a fight between civilization and barbarism."

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Suspects

Police shot dead an alleged attacker, identified by Interior Minister Nehammer as 20-year-old Kujtim Fejzulai.

Police had used explosives to blast their way into the apartment of the dead man, who had been armed with an automatic rifle, a hand-gun and a machete.

According to police, he had been wearing a belt carrying explosives that turned out to be fake, with authorities identifying the man as a convicted ISIL sympathizer and someone who was already known to Austria's security services.

The interior ministry said Fejzulai, a dual citizen of Austria and North Macedonia, had been sentenced to 22 months in jail in April 2019 for attempting to travel to Syria to join ISIL. He had been released early in December.

Nehammer said Fejzulai had posted a photo on his Instagram account before the attack, showing himself with two weapons that he is thought to have used. There was no immediate claim of responsibility for the attack despite supporters of ISIL, praising the attack on the messaging service Telegram.

The interior minister said video material had been seized from the home of the known assailant during a search and police were investigating his potential connections.

"It's difficult for us at the moment to define whether the attack was carried out by one perpetrator or more than one," said Gerhard Puerstl of the Vienna police. 

However, Nehammer had earlier said: "According to what we currently know, there is at least one attacker who is still on the run."

On Tuesday morning, officials attempted to play down the suggestion, saying it was only a possibility but one they could not rule out.

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Manhunt 

Helicopters continued to fly overhead in Vienna as hundreds of police fanned out across capital on Tuesday.

With pockets of the center still cordoned off as the police manhunt got under way, the government urged Vienna residents to remain in their homes and keep away from all public places or public transport. The interior minister said children would not be expected to go to school on Tuesday.

Reinforcements have been called in from neighboring states, according to a police spokesman, and at least 1,000 officers are involved in the hunt, as states on Austria's border stepped up security checks at their frontiers. 

The interior minister told APA news agency that 15 properties had been searched. The agency later reported two suspects had been arrested in the Austrian town of St. Poelten. According to ORF, another person has been detained in connection with the case in the city of Linz.

A witness to the attack, Vienna rabbi Schlomo Hofmeister, said he saw one gunman but could not be sure there were no others.

"I saw one person. Later, I saw videos and I'm not sure it was the same one. I find it very difficult to identify someone in a fraction of a second," he said. 

Large numbers of security forces are still guarding sensitive sites, including an area near the opera house, one of the points of attack. Kurz said that as police concentrated on an anti-terror operation, the army would take over the security of major buildings in Vienna.

"We are experiencing difficult hours in our republic," said the chancellor on Twitter.

"Our police will act decisively against the perpetrators of this repulsive terror attack. We will never be intimidated by terrorism and we will fight this attack with all means."

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International response

Across Austria, flags were lowered to half mast on public buildings and people observed a minute of silence at midday local time, as condolences poured in from leaders and top officials around the globe.

U.S. President Donald Trump said in a tweet that "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. The U.S. stands with Austria, France, and all of Europe in the fight against terrorists, including radical Islamic terrorists."

Democratic presidential candidate Joe Biden condemned what he called a "horrific terrorist attack." Adding: "We must all stand united against hate and violence."

EU Council President Charles Michel tweeted that the bloc "strongly condemns this cowardly act," while in London, UK Prime Minister Boris Johnson said the "UK's thoughts are with the people of Austria – we stand united with you against terror."

Russian President Vladimir Putin called the Vienna shooting a "cruel and cynical" crime, while German Chancellor Angela Merkel said: "The fight against these assassins and those who instigate them is our common struggle." 

President Emmanuel Macron of France tweeted: "We French share the shock and sorrow of the Austrian people."

On Thursday, three people were killed at a church in French Riviera city of Nice and a schoolteacher was beheaded by a suspected Islamist outside Paris on October 16.

Prior to Monday night, Austria's capital had been spared the kind of deadly attacks witnessed in Paris, London, Berlin and Brussels, among others, in recent years, despite being part of the U.S.-led Global Coalition to Defeat ISIS formed in 2014.

Video production: Giulia Carbonaro and Natalia Luz