Gunmen armed with rifles have opened fire in six different locations in central Vienna, killing two people and wounding several more, police say.
Austrian Chancellor Sebastian Kurz called it a "repulsive terror attack" and said one gunman was also killed.
Police were searching for at least one attacker who was still at large, the interior minister said.
The shootings took place near the central synagogue but it is not yet clear if that was the target.
Mayor Michael Ludwig said 15 people had been wounded, seven of them seriously. One woman died from her injuries in hospital, he added, while the other victim was killed at the scene of one of the shootings.
A police officer was among the injured, the interior ministry said.
The attack happened just hours before Austria imposed new national restrictions to try to stem rising cases of coronavirus. Many people were out enjoying bars and restaurants which must close until the end of November.
European leaders strongly condemned the shooting. British Prime Minister Boris Johnson said he was "deeply shocked by the terrible attacks".
Police said the incident began near the Seitenstettengasse synagogue, which is the main temple in Vienna.
An officer guarding the synagogue was among the wounded, newspaper Kronen Zeitung reported.
It was not immediately clear how many attackers took part in the shooting. Austrian media said one person had been arrested, citing the interior ministry.