Austria authorities say schools in Vienna will be closed Tuesday as police hunt for suspects in the shooting deaths of four citizens and the wounding of several more.
Residents have been told to stay away from the city center and to avoid public transport.
The authorities now say the attacks had an "Islamist motive." Interior Minister Karl Nehammer said the gunman who was shot dead by police was "radicalized" and an ISIS sympathizer.
He was armed with an assault rifle among other weapons. He was wearing a fake explosive vest.
One of the shooters was killed by police but at least one other has to date eluded them. The army has been called in to secure the city while police look for the suspect or suspects, Chancellor Sebastian Kurz said. He called the killings a "repulsive terrorist attack."
"Upon hearing shots, we looked down (from) the windows and saw the gunmen shooting at the guests of the various bars and pubs," witness Rabbi Schlomo Hofmeister told London's LBC radio. "The gunmen were running around and shooting at least 100 rounds or even more in front of our building," he said.
Three people died in hospital Tuesday, another was killed instantly Monday and at least 15, including a police officer, were wounded when an unspecified number of shooters opened fire at restaurants and cafes near the central synagogue before a pandemic lockdown Monday.
Kurz said several assailants were still on the loose and were equipped with automatic weapons.
"We've brought in several special forces units that are now searching for the presumed terrorists. I'm therefore not limiting it to an area of Vienna because these are mobile perpetrators," Reuters quoted Interior Minister Karl Nehammer as saying.
Unverified video on social media showed the gunmen walking through the streets and opening fire at people at random, injuring several.
Authorities continue to investigate the motive. Oskar Deutsch, director of the Jewish Community of Vienna, said it wasn't clear if the synagogue was the target of the attack. The temple was closed at the time.
Australia Prime Minister Scott Morrison said Australia "stands firm with our Austrian friends" following the shootings in Vienna. "Deeply shocked by the awful terror attacks in Austria. The situation remains fluid and details of the attack are still not clear," he said in a Tweet on Tuesday.
British Prime Minister Boris Johnson said he was "deeply shocked by the terrible attacks in Vienna...we stand united with you against terror," the Guardian reported earlier.
Meanwhile, authorities warned people not to share videos or spread rumors of the attack on social media because it could jeopardize their operation.
