Several people have been injured in a shooting in central Vienna, police say.
The interior minister described the incident as a “terror attack” and said that one attacker had died.
Another was “on the run” in the Austrian capital after the shooting.
A large-scale security operation is under way.
Police have urged people to avoid all public spaces in the area and not to take public transport.
Road blocks have been set up around the city centre. Footage posted on social media showed people running as what was reported to be gunshots could be heard.
The shooting reportedly took place on a street near a synagogue.
Jewish community leader Oskar Deutsch tweeted that it was unclear if the Vienna synagogue was targeted in the attack as it was closed at the time.
“It sounded like firecrackers, then we realised it was shots,” said one eyewitness quoted by public broadcaster ORF, according to AFP news agency.