At least one person is dead and a police officer is among several who are injured after a suspected terror attack carried out by multiple suspects across six locations in Vienna.
Vienna police have said the attack was carried out by several suspects armed with rifles.
Austrian public broadcaster ORF-TV earlier reported that several people were killed.
Police have confirmed one suspect was shot and killed by police.
The force also said a person is "deceased" but it is not clear if they are referring to the killed suspect or a victim.
Vienna police have said the shootings took place across six locations in the Austrian capital, with the first gunshots heard at 8pm local time at the Seitenstettengasse synagogue.
Austrian public broadcaster ORF-TV is reporting that several people were killed.
Fifteen people who were injured in the attack are being treated in treated in Vienna hospitals, seven of whom are seriously injured, a reporter for the broadcaster has said.
The office of Austria's top security official Karl Nehammer's reportedly said earlier one attacker could be on the run.
The interior ministry is reported to have said one suspect has been arrested.
Local media reported earlier that a synagogue had been attacked and shots fired in the area of a nearby square, Schwedenplatz, while there were unconfirmed reports of coordinated attacks nearby.
Oskar Deutsch, the head of the Jewish community in Vienna, said shootings took place in the street where the city's main synagogue is located but that it wasn't clear whether the house of worship had been targeted.
Mr Deutsch tweeted that the synagogue was closed at the time of the shootings.
Officers said the operation in the centre of the city was ongoing and urged people to avoid all open spaces and public transport.
Police tweeted earlier: "There are several injured persons.
"We are on site with all available forces. Please avoid all public squares in the city."
Police added that the exact circumstances of the incident were still being determined.
State broadcaster ORF said the operation is taking place at a synagogue.