The blast – believed to be caused by a gas explosion – tore through the fourth district of the Austrian capital today.
Several people were hurt although the extent of their injuries is unclear at this stage, the fire brigade confirmed.
Cops sai the blast happened at the Pressgasse and Schäffergasse streets shortly after 4.30pm local time.
Multiple floors of two buildings have been completely destroyed.
A fire spokesman also said the blast was so powerful it left a huge crater in front of the buildings.
Emergency services are on the scene, with firefighters searching the buildings for anyone injured.
Neighbouring properties have also been evacuated.
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