Austrians observe minute's silence after attack

Church bells rang during a minute of silence to honour the victims of the attack, as shocked local residents who have always felt safe in their city appealed for the country to unite.

Tamirlan Dadayev, whose boss at a local cafe was in hospital after being injured in the attack, said he could have never imagined something like this would happen in Vienna.

"Everyone is mourning, the atmosphere is negative at the moment. Friends are afraid," said Dadayev.

As Austrian police continued the hunt for suspects, the country's president gave an address to the nation on the "worst (attack) in our recent history."

"We will defend and protect ourselves and our values," President Alexander Van Der Bellen said.