Police officers are on duty on a street in Vienna, capital of Austria, Nov. 2, 2020. (Photo by Georges Schneider/Xinhua)

Gunmen opened fire at multiple locations across central Vienna on Monday, killing at least four people and wounding several more in what Austrian Chancellor Sebastian Kurz described as a "repulsive terror attack," with a huge manhunt under way for the assailants.

One of the suspected killers, identified as an Islamic State group sympathiser, was shot dead by police who said they were searching for at least one more assailant still at large.

The attacks, in six locations including near a synagogue in the center of town, were carried out by "several suspects armed with rifles," police said.

The shooting began just hours before Austria was to reimpose a coronavirus lockdown, with people out in bars and restaurants enjoying a final night of relative freedom.

The attacks started at around 8 pm when the first gunshots were heard in the city's centrally located first district.

In a press conference early Tuesday, Interior Minister Karl Nehammer said: "According to what we currently know, there is at least one attacker who is still on the run."

Speaking to public broadcaster ORF, Austrian leader Kurz had said that the attackers were "were very well equipped with automatic weapons" and had "prepared professionally."

Earlier, he tweeted: "Our police will act decisively against the perpetrators of this repulsive terror attack," adding that "we will never be intimidated by terrorism and we will fight this attack with all means."

Kurz said that while police were concentrating on the anti-terror operation, the army would take over the security of major buildings in Vienna.

Nehammer urged Vienna residents to remain in their homes and keep away from all public places or public transport. 

He said that children would not be expected at school on Tuesday in Vienna.

Sirens and helicopters could be heard in the city center as emergency services responded to the attack.

The location of the initial shooting was close to a major synagogue.

The president of Vienna's Jewish community Oskar Deutsch said that shots had been fired "in the immediate vicinity" of the Stadttempel synagogue, but added that it was currently unknown whether the temple had been the target of an attack.

AFP