Austrian police have arrested 14 people who are believed to be linked to the convicted jihadist who killed four people and injured 22 others in a terrorist rampage in Vienna.

Police ramped up their search for potential suspects amid concerns there were other shooters on the loose.

Austrian police raided 18 properties after it was revealed the 20-year-old gunman, who was killed by police minutes after opening fire on crowded bars, was an Islamic State sympathiser.

The army was tasked with guarding sensitive sites while at least 1000 officers searched for accomplices.

Austria’s interior minister Karl Nehammer said 14 people with suspected links to the gunmen, identified as Kujtim Fejzulai, had been detained.

Though authorities believe the gunmen may have acted alone on Tuesday.

An elderly man and woman, a young passer-by and a waitress were killed, and 22 people including a policeman were wounded.

So far four people are confirmed dead and 17 wounded. Photo: Getty

Vienna’s mayor said three people were still in critical condition.

In a televised address, Chancellor Sebastian Kurz told Austrians: “This is not a conflict between Christians and Muslims or between Austrians and migrants. No, this is a fight between the many people who believe in peace and the few (who oppose it). It is a fight between civilisation and barbarism.”

The attack followed shortly after deadly assaults by lone jihadists in Nice and Paris, where some Muslims have been angered by publication of satirical caricatures of the Prophet Mohammed.

The centre of Vienna was largely deserted on Tuesday, with many shops closed, though Austrian authorities played down earlier suggestions that other shooters might still be on the loose.

Mr Nehammer said footage of the incident filmed on numerous mobile phones showed no evidence of a second gunman, although the possibility had not been completely ruled out.

Fejzulai, an Austrian-born son of immigrants from North Macedonia, was wearing an explosive belt that turned out to be fake.

Vienna’s police chief said he was killed nine minutes after starting his rampage.

People place candles at a crime scene in the city center the day after the deadly shooting spree. Photo: Getty

Fejzulai was a dual citizen of Austria and North Macedonia, who had been sentenced to 22 months in jail in April last year for attempting to travel to Syria to join the Islamic State group but was released early, in December.

Mr Nehammer said Fejzulai had attended a de-radicalisation programme, but that “despite all the outward signs that he was integrating into society, the assailant apparently did exactly the opposite”.

Fejzulai had posted a photo on a social media account before the attack, showing himself with weapons, Mr Nehammer said.

There was no immediate claim of responsibility for the attack.

Officials said the perpetrator had been armed with an automatic rifle, a hand-gun and a machete.

Witnesses described crowds being fired on in bars as people enjoyed a last evening out before the start of a coronavirus curfew.

The government announced three days of national mourning and held a minute’s silence at noon on Tuesday.

-with AAP