Austrian interior minister says police found evidence that dead attacker was radicalized, sympathized with Islamic State terror group.

Media reports say at least one gunman killed four people and seriously injured several others before being shot dead by police in an attack in the Austrian capital, Vienna, that officials called Islamist terrorism.

A gunman killed by the police was an Islamic State “sympathizer,” the interior minister said, according to The New York Times.

The gunman killed by the police was reportedly wearing a fake explosive device.  

The police have been searching for possible accomplices, with about 1,000 officers fanning out across Vienna.

But they also appeared to raise the possibility that the slain gunman had acted alone, though the authorities had previously said there were multiple attackers. 

A terrorist attack in central Vienna on Monday night left at least four people dead and many others wounded, including a police officer, government officials said.

Austrian Chancellor Sebastian Kurz said he had called in troops to ensure the security of Austria’s official buildings, freeing up the police to “concentrate fully on the fight against terror.”

The area where shots were first reported is a tight web of streets packed with bars and pubs, known locally as the “Bermuda Triangle.” It is also home to Vienna’s main temple, the Seitenstettengasse synagogue — but it was not clear what the intended target, or targets, of the attackers had been.