Austria was grappling on Tuesday with a brutal attack in which a gunman, whom officials described as an ISIS sympathizer and who was wearing a fake explosive device, opened fire on Monday night in the heart of Vienna, the capital, killing at least four people.
By Tuesday morning, around 1,000 police officers had fanned out across the city to patrol the streets. Leaders addressed the nation, and an anxious public, largely confined to their homes amid a new coronavirus lockdown, waited for answers.
But some crucial details about the violence the night before, and its perpetrator, remained unclear.
Chancellor Sebastian Kurz said in an address to the nation on Tuesday morning that the shooting was “definitely an Islamist terrorist attack,” which he called “an attack out of hatred, hatred for our basic values.”
“We often see ourselves as a blessed island where violence and terror is only known from abroad,” he said. “But the sad truth is: Even if we live in a generally safe country, we don’t live in a safe world.”
The police killed a gunman, whom Interior Minister Karl Nehammer described as an Islamic State “sympathizer” at a news conference on Tuesday morning.
The police appeared to suggest that the man had acted alone, though the authorities had previously said that there were multiple attackers.
Austria’s government announced a three-day official mourning period beginning on Tuesday, in which flags on public buildings will be lowered to half-staff. A minute’s silence was held at noon.
On Tuesday morning, Harald Sörös, an Interior Ministry spokesman, said that a second woman had died of her injuries, bringing the number of victims to four. Fourteen people were wounded, six of them seriously, he said.
Monday’s violence comes after a recent terror attacks in France — including the beheading of a teacher and a knife attack at a church — that have both been linked to Islamist extremists. But Mr. Kurz warned against making assumptions about the Muslim community.
“This is no fight between Christians and Muslims, or between Austrians and migrants,” he said. “This is a fight between civilization and barbarism.”
Ümit Vural, president of the Islamic Faith Community in Austria, condemned the “cowardly, revolting attack,” calling it “an attack on our Vienna” and “an attack on all of us.”
“Our democracy, our freedom and liberal order is stronger than violence and terror,” he said.
What do we know about the gunman who was killed, and the others arrested?
The attacker who was killed was a 20-year-old Vienna-born man whose parents came from North Macedonia, a senior official confirmed, speaking anonymously because the person was not authorized to be named. The Austrian intelligence service was apparently aware of him because he was one of about 90 Austrians who had planned to join the Islamic State in Syria, and he was blocked from traveling to the region.
He was sentenced last year to 22 months in prison because of his attempt to travel to Syria and join the extremist group. Most of the Islamists in Austria who had tried to travel to the region and are known to the intelligence authorities were radicalized sometime between 2014 and 2016 and many were ethnically Bosnian, Kosovar, Albanian, Chechen or Kurdish.
On Tuesday morning, Karl Nehammer, the interior minister, described the gunman as an Islamic State “sympathizer” but did not reveal the man’s name. He said the police had searched his apartment.
At least 14 people were also arrested in the aftermath of the shooting on the suspicion that they were linked to the attack, and 18 raids were conducted, according to a senior Austrian official, mostly in Vienna but also in St. Pölten, an hour west of the city, and in Linz, about 10 miles west of Vienna toward the German border.
Dmitri Y. Lyubinsky, the Russian ambassador to Austria, said that people from Russia’s predominantly Muslim Northern Caucasus region were among those detained by the Austrian authorities.
“There is information about immigrants from various Balkan countries, from the Muslim world and from the Northern Caucasus being among those detained,” Mr. Lyubinsky said on an afternoon talk show aired on Russian state television on Tuesday. “There is no further detail at the moment.”
Russia has long struggled with Islamist extremism in Chechnya, a restive republic in the Northern Caucasus, and many Chechens have emigrated to Europe. The 18-year-old assailant who beheaded a schoolteacher in France last month before being fatally shot by the police was from Chechnya.
Mr. Lyubinsky did not suggest that the Austrian attack was connected to the French attack and did not specify how he knew about the backgrounds of the people detained. He said Russia was in contact with Austrian law enforcement authorities.
On Tuesday morning, the police appeared to suggest that the Vienna assailant had acted alone, though the authorities had previously said that there were multiple assailants.
The cobbled streets of the center of Vienna, normally full of tourists, government employees and other citizens, was largely empty on Tuesday, save for hundreds of heavily armed police officers. School attendance was optional and residents were encouraged to stay home.
Church bells rang out at noon, as the city paused for a moment to honor the victims. Among them, Austria’s largest church bell — the “Pummerin,” which hangs in the northern tower of St. Stephen’s Cathedral and is only used for special events — rang out.
The attack on Monday came hours before the country entered a lockdown to combat the coronavirus, with many people having gathered outdoors in Vienna before it came into force. Hundreds of others were trapped in the city’s famed opera house and the national theater, both of which were evacuated by the police hours after the curtains had fallen.
“You could feel a lot of people wanted to get out one more time before lockdown starts,” said Ameli Pietsch, 23, who was in the area an hour before the attack. “It was a mild evening, and lots of people were outside.”
All of that changed in a moment. People scrambled from the streets to shelter in restaurants, and all trams and subways in the city’s center were halted as the police urged residents to shelter in place.
The sound of sirens and helicopters filled the night air as people struggled to absorb what was happening.
Said Farnaz Alavi, 34, a human resources consultant in Vienna, said, “We are in shock.”
Mr. Kurz said in his speech Tuesday morning that the gunman had killed four people at close range — an older man, an older woman, a younger man passing by and a waitress working in a restaurant.
But he also urged citizens to remember that “our enemy is never all those belonging to a religion, our enemy is never all the people that come from a particular country” but rather “our enemy is extremists and terrorists.”
“They do not belong in our society,” he added.
With the target unclear, the authorities discouraged speculation.
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 the attack’s intended target, or targets, was unclear.
The president of the Jewish Religious Community in Austria, Oskar Deutsch, said on Twitter that the initial shooting had occurred “in the immediate vicinity” of the temple, but that it was closed at the time.
“It is not clear right now whether the main temple was the target,” he said. Jewish institutions across the city were closed on Tuesday, the Jewish Community of Vienna said on its website.
The police took to Twitter to urge restraint.
“Please don’t share any rumors, accusations, speculations or unconfirmed numbers of victims,” they said. “That does not help at all! Stay inside, take shelter. Keep away from public places.”
As news of the attack unfolded, several people posted dramatic videos on social media of what appeared to be the shooting and its aftermath.
One showed people helping a wounded person who was lying in a pool of blood, just outside a restaurant on Ruprechtsplatz and less than a mile from the Austrian Parliament. Several chairs in the restaurant’s outdoor area had been overturned, as if abandoned in a hurry.
Another video showed a man emerging from a bar or restaurant, then firing a rifle twice down a street. And a separate video appeared to show the same gunman on the same street, shooting a man with a long gun at close range, then returning seconds later to shoot him twice more.
The Vienna police, in a post on Twitter, pleaded with witnesses not to post videos and pictures to social media, but instead to send them to the authorities.
The city has found itself in the cross hairs before.
Austria — and Vienna in particular — has been a target over the years for terrorist attacks, often with deadly outcomes. Religious and political tensions, sometimes with no clear connection to Austria, have led to sporadic violence.
In 1975, a meeting of the Organization of the Petroleum Exporting Countries in the city was stormed by six men with submachine guns. They killed three people and took at least 60 hostages.
A group that claimed responsibility cast the attack as “an act of political contestation and information” aimed at “the alliance between American imperialism and the capitulating reactionary forces in the Arab homeland.”
In 1981, Heinz Nittel, a leader of the Austrian Socialist party and head of the Austria-Israel Friendship Society, was assassinated outside his home by an assailant associated with a militant Palestinian group.
Two people were killed in 1981 when terrorists attacked a synagogue with grenades and firearms. Just after Christmas in 1985, panic engulfed the Vienna airport when three gunmen stormed the check-in lounge and opened fire with submachine guns, killing three and wounding dozens.
Witnesses at the time said the attack began as an El Al Israel Airlines flight was boarding. The attack appeared to be coordinated with another El Al check-in 10 minutes earlier in Rome.
From 1993 to 1997, a series of mail bombs and other explosive devices, including one that wounded the mayor of Vienna, stoked fears of rising neo-Nazi terrorism in the country. The man who was convicted in the attacks said that his goal had been to create a reunification of German-speaking areas.
Melissa Eddy, Christopher F. Schuetze and Katrin Bennhold reported from Berlin, and Megan Specia from London. Reporting was contributed by Anton Troianovski from Moscow, Aurelien Breeden from Paris, Livia Albeck-Ripka from Darwin, Australia, Joe Ritchie from Hong Kong, and Christoph Koettl, Farnaz Fassihi and Emmett Lindner from New York.