READ MOREA fire broke out after the blast at around 9am (08:00 GMT) in Paris's 9th arrondissement (district), a residential and shopping area, police and AFP journalists said.
Images posted on Twitter showed debris covering the street and the lower part of the building blown out and in flames. Parked cars were also damaged in the blast.
An AFP photographer saw at least one person being carried away on a stretcher from the building by firefighters.
Police said nine people were seriously injured.
Firefighters worked to extinguish the blaze and exacuate some people from the building using ladders while emergency workers treated some of the injured at the scene. ■