At least 36 people have been injured after a gas leak caused an explosion in Paris, emergency services in the French capital say.
The blast occurred at a bakery at 9 a.m. local time on Saturday, as firefighters were responding reports of the leak.
"The human toll is heavy -- 12 people seriously injured, of which three are firefighters," prosecutor Rémy Heitz told reporters.
Five people, including two of the injured firefighters, are in a critical state, Heitz added. An additional 24 people were also injured by the blast, but not critically, a spokesman for the Paris Fire Brigade said.
Pictures from the scene showed smashed windows and scattered debris across the street, as fire crews evacuated people from apartments above the bakery.
"At this stage, we can tell the origin of the explosion is accidental, a gas leak, but we should remain prudent as an ongoing investigation will determine the causes of this," Heitz said.
French Interior Minister Christophe Castaner, who visited the scene with Prime Minister Edouarde Philippe and the city's mayor Anne Hidalgo, wrote earlier on Twitter that the toll of victims "will be heavy."
More than 200 firefighters are responding to the incident, Castaner wrote. "My first thoughts go to those injured and their loved ones," he added.
Police advised the public to stay away from the area, on Rue de Trevise in the 9th arrondissement of the French capital, and to make space for emergency vehicles.