Terrified diners hid under tables as police scoured restaurants and bars looking for the gunmen responsible for the Vienna terror attack.
At least two civilians were shot dead by attackers who struck at around 8pm local time in the Austrian capital.
A huge manhunt is underway as police and the army search for the attackers, one of whom has been shot and killed.
A 53-year-old Lower Austrian who had a business meal in a local restaurant on Monday evening was surprised by the shots during the terrorist attack in downtown Vienna.
“We heard the shots, and then it was said, lights off, doors closed,” the man said in an interview with the APA.
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“Then all the guests lay down on the floor. The fear among the guests was insane.” Nobody was injured in the restaurant.
Rabbi Schlomo Hofmeister said: “The perpetrator moved in the direction of the Hoher Markt and Ruprechtskirche and shot at the people who were sitting in the Schanigarten in Judengasse and Seitenstättengasse. He did not aim at the city temple.
Another witness said: “I’ve heard gunshots, but I’ve never heard anything like it. In my naivety I thought it was firecrackers.”
Witness Chris Zhao was in a nearby restaurant when the shooting started.
“There were victims. Sadly, we also saw a body lying down the street next to us.”
He told the BBC: “We heard noises that sounded like firecrackers. We heard about 20 to 30 and we thought that to be actually gunfire. We saw the ambulances… lining up.
One attacker was shot dead by police with two civilians, one of them a woman, killed in the rampage.
A police officer is also thought to have been shot and seriously injured.
Vienna mayor Michael Ludwig said 15 people were admitted to hospital, seven with serious injuries.
Police urged people to avoid all open spaces and public transport in the city. They also said trams and buses were not stopping and urged social media users not to post videos of the police operation.
Oskar Deutsch, the head of the Jewish community in Vienna, said the shooting took place in the street where the city’s main synagogue is located but that it wasn’t clear whether the house of worship had been targeted.
The synagogue was already closed at the time of the shooting, Deutsch tweeted. A neighbouring restaurant was also closed.
“We are living in the compound of the synagogue. Upon hearing shots we looked down (from) the windows and saw the gunmen shooting at the guests of the various bars and pubs,” 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.
Videos circulated on social media of a gunman running down a cobblestone street shooting and shouting.
French President Emmanuel Macron vowed Europe would not bow to terrorists following the shootings.
“We French share the shock and sorrow of the Austrian people following the attack in Vienna,” Macron tweeted in both French and German.
“After France, it is a friendly nation that has been attacked. This is our Europe. Our enemies must know who they’re dealing with. We will concede nothing.”
Both Boris Johnson and Home Secretary Priti Patel tweeted to express solidarity with Austria.
Mr Johnson said: “I am deeply shocked by the terrible attacks in Vienna tonight.
“The UK’s thoughts are with the people of Austria – we stand united with you against terror.”