At least four people were killed and 15 seriously injured in multiple shootings by suspected terrorists in the Austrian capital on Monday evening, according to local police.

“The attack had an Islamist motive,” the Vienna Police wrote on Twitter on Tuesday morning.

There is at least one perpetrator, who was shot by police, it said, noting that an explosive device worn by the perpetrator turned out to be a dummy.

The police have searched the house of the perpetrator and are evaluating video recordings related to the attack. 

The Austrian government declared three days of mourning for victims following the attack.

“Our thoughts and our compassion are with the victims, the injured and their families in these very difficult hours for the republic of Austria,” Chancellor Sebastian Kurz said before a cabinet meeting.