A massive explosion at a north central Paris bakery has claimed a fourth life, with rescuers uncovering the body of a missing woman amid a mountain of debris and wrecked cars.

Those killed on Saturday morning in the Rue de Trevise included a Spanish tourist and two firefighters, one of whom had been buried under debris for several hours.

“Unfortunately the human toll is particularly serious,” France’s Interior Minister Christophe Castaner told reporters at the scene.

A Spanish woman was on holiday with her husband when her body was discovered in the rubble after a suspected gas leak triggered the explosion.

Her death was first revealed by Spanish Foreign Minister Josep Borrell on Twitter and later confirmed by Spanish newspaper El Confidencial who also revealed that her husband had been unharmed.

Nine people are still in critical condition, with 45 others less seriously injured, Paris Fire Department spokesman Eric Moulin said.

About 30 firefighters began the search on Sunday to locate potential victims from the blast which damaged 12 neighbouring buildings.

A general view shows debris and car wreckage following the explosion. Photo: Getty

Paris firefighters were already on the scene to investigate a suspected gas leak at the bakery when the explosion happened, shattering nearby storefronts and damaging buildings hundreds of metres away.

“The situation is now under control,” France’s Interior Minister Mr Castaner said.

He said more than 200 firefighters were involved in the rescue operation.

David Bangura was at a nearby hotel when he saw a huge fire erupt in the building where the explosion happened.

“There was broken glass everywhere, storefronts were blown out and windows were shattered up to the third and fourth floors,” Mr Bangura, 38, said.

As he approached the scene, Mr Bangura said he saw a woman crying for help from the first floor of a building.

“Help us, help us, we have a child,” he recalled her as saying.

Distressing images coming out of central #Paris – huge explosion at a bakery cafe on a Saturday morning. Early reports it may have been caused by gas leak. More info to come. pic.twitter.com/D68oh8I4bB

— Trent Murray (@trent_murray) January 12, 2019

Paris Mayor Anne Hidalgo, who was also at the scene, extended a “message of affection and solidarity” to the victims.

Temporary accommodations were provided for about 40 residents while dozens of others have been housed by family and friends.

The city hall of Paris’ 9th arrondissement was offering meals and collecting clothes on Sunday to help evacuated people.

-with AAP