(YWN) At least one Islamic extremist—a 20-year-old armed with an automatic rifle and a fake explosive vest—rampaged through a crowded Vienna district Monday night, leaving four people dead before being killed by police.

The suspect was identified as Kujtim Fejzulai, a young Austrian-North Macedonian dual citizen with a previous terror conviction. Unverified videos showed him firing off bursts apparently at random as he ran through the streets.

Police have arrested several other people and searched 15 houses and apartments, Interior Minister Karl Nehammer reported.

In addition to the four killed, Chancellor Sebastian Kurz said, a police officer was shot and wounded and another 14 people were hurt.

Authorities are still trying to determine whether additional attackers are on the run. People in Vienna were urged to stay home if possible on Tuesday and children did not have to go to school. Authorities urged people to avoid all open spaces and public transport in the city.

Kurz said he could not yet rule out an anti-Semitic motive for the attack as the shooting began outside Vienna’s main shul and a Jewish restaurant.