The shootings occurred in the early evening, a few hours before the entry into force of a containment of Austria to fight the Covid-19 pandemic.
Hundreds of shots could have been fired, according to the Viennese police who report "several attackers with guns" and count a total of "six crime scenes".
One of the attackers was shot dead by the police, who intervened quickly on the scene.
The shootings are said to have injured at least 15 people, including a policeman, and one civilian dead.
On the spot, the police forces mobilized in large numbers to guard the premises, located not far from the Opera, noted an AFP photographer, while passers-by fled.
The minister called on residents to remain cautious and stay at home.