Several people have been wounded in central Vienna and some probably killed in exchanges of gunfire in what is believed to be a terror attack.
An area of central Vienna has been cordoned off and police say a large deployment of officers is under way.
Interior Minister Karl Nehammer told Austrian broadcaster ORF late on Monday the attack was believed to have been carried out by several people.
“At the moment I can confirm we believe this is an apparent terror attack,” he said.
“We believe there are several perpetrators. Unfortunately there are also several injured, probably also dead.”
A police officer was shot and seriously injured and one person was arrested, news agency APA said, citing the Interior Ministry. One person had been killed, likely one of the attackers, local media reported.
Local media reported also that a synagogue had been attacked and shots had been fired in the area of a nearby square, Schwedenplatz. There were unconfirmed reports of co-ordinated attacks nearby.
“Shots fired in the Inner City district – there are persons injured – KEEP AWAY from all public places or public transport,” the police said on Twitter.
Jewish community leader Oskar Deutsch said on Twitter it was not clear whether the Vienna synagogue and adjoining offices had been the target of an attack, and said they were closed at the time.
Videos began to circulate on social media of a gunman running down a cobblestone street shooting and shouting.
Vienna police urged people not to share videos and photos via social media.
“This jeopardizes police forces as well as the civilian population,” they said on Twitter.
In 1981, two people were killed and 18 people injured during an attack by two Palestinians at the same synagogue.
In 1985, a Palestinian extremist group attacked Vienna airport with hand grenades and attack rifles, killing three civilians.
In recent years Austria has been spared the sort of large-scale attacks seen in Paris, Berlin and London.
In August, authorities arrested a Syrian refugee suspected of trying to attack a Jewish community leader in the city of Graz.