Earlier reports said one passerby had been killed. The Interior Ministry said several people had died, but provided no exact figures.

"After this terrible crime, after the murder of a man, a woman died... Fifteen people were taken to hospitals, assistance was provided to seven seriously injured. I hope they will soon be able to leave the hospitals," Ludwig told ORF.

A group of unidentified persons carried out a series of attacks with shooting in downtown Vienna on Monday.

The attacks in particular targeted a synagogue, according to media reports. Austrian Chancellor Sebastian Kurz said the incident was a terrorist act.

According to law enforcement, several people were seriously wounded, including a policeman, one attacker was neutralized, and at least one more attacker was being sought.