The shooting happened hours before Austria was to re-impose a coronavirus lockdown, with people out in bars and restaurants enjoying the final night of relative freedom.
Authorities urged Vienna residents to remain in their homes and keep away from all public places or public transport following the attack which Austrian Chancellor Sebastian Kurz described as a “repulsive terror attack”.
Police said the incident began near the Seitenstettengasse synagogue, which is the main temple in Vienna. It is not yet clear if that was the main target.
Frequent sirens and helicopters were heard in the city centre as emergency services responded to the attack. Large numbers of police officers were also seen near Vienna’s world-famous opera house.
Interior minister Karl Nehammer said: “This is the hardest day for Austria for several years. We’re dealing with a terror attack the severity of which we haven’t experienced in Austria for a long time.”
He added border checks were being reinforced and that children would not be required to attend schools till further information.
French President Emmanuel Macron expressed support for Austria amid the attack and tweeted: “We French share the shock and grief of the Austrian people struck this evening by an attack in the heart of their capital, Vienna. After France, a friendly country is attacked. This is our Europe. Our enemies must know who they are dealing with. We will not give up.”
France has been on high alert following an attack near the former office of Charlie Hebdo on September 25 and the beheading of a history teacher in a Paris suburb on October 16.
Prime Minister Narendra Modi also expressed solidarity with Austria by tweeting: “Deeply shocked and saddened by the dastardly terror attacks in Vienna. India stands with Austria during this tragic time. My thoughts are with the victims and their families.”