As per reports, one of the gunmen was shot dead by police who said they were hunting for at least one more attacker still at large.
The attack is a grim remindedr of the 26/11 Mumbai attacks where a series of co-ordinated attacks were similarly carried out at multiple locations, though at a much larger scale.
The photos and video on social media present a harrowing picture,. Videos broadcast by private broadcaster "Oe24" showed a masked shooter who fired at least two shots in the street. Another video showed a large pool of blood outside a restaurant
Here are some of the footages on social media showing live action at the time of the attack:
There were several people injured, the Vienna police said on Twitter. According to a ministry spokeswoman, a police officer was shot and seriously injured in the exchange of fire near Schwedenplatz.
"We are with all possible forces in action," wrote the police on Twitter, calling on people to avoid all public places in the city.
Watch Report: