Rescuers have found a woman’s body under the charred rubble of a bakery in Paris that was blown apart by a powerful explosion, bringing the overall death toll to four.

The incident, apparently caused by a gas leak, injured dozens and devastated the street it was on as it blasted out windows and overturned nearby cars, French authorities said.

Witnesses described the sound of the explosion as deafening. Firefighters pulled injured victims out from broken windows and evacuated residents and tourists as a fire raged and smoke billowed over Rue de Trevise in the 9th arrondissement of north-central Paris.

Charred debris and broken glass covered the pavement around the apartment building housing the bakery, which resembled a blackened carcass, and people were trapped inside nearby buildings.

Interior Minister Christophe Castaner paid homage to the courage of rescuers, who saved the life of one firefighter who was buried under the rubble for 2 hours.

The French Interior Ministry said two firefighters and a female Spanish tourist were killed by the blast and about 10 of the 47 wounded were in critical condition.

He told reporters at the scene “unfortunately the human toll is particularly serious.”

“As firemen were looking for a gas leak in the building, a dramatic explosion took place,” he said.

French authorities corrected the figure of four dead given earlier by France’s interior minister.

Paris prosecutor Remy Heitz said the cause of the blast appeared to be an accidental gas leak. He said Paris firefighters were already at the scene to investigate a suspected gas leak at the bakery when the explosion happened about 9am (local time/8pm AEST).

French journalists at the scene said the windows of buildings along the entire block on the Rue de Trevise in the commercial district were blown out during the explosion.

Photographs show twisted bicycles, mangled rubbish bins and building debris flung violently across the road.

Cars were upturned and on fire, and glass scattered across the streets and footpaths.

Despite initial fears of a terror attack police quickly ruled the blast was caused by a gas leak in a patisserie.

Spanish Foreign Minister Josep Borrell tweeted that “I deeply regret the death of three people after the explosion in central Paris, including a Spanish woman.”

He shared condolences to her relatives and “wishes for a quick recovery to the other injured Spaniard.”

The Spanish newspaper El Pais reported the woman was a tourist staying in a hotel near the bakery, which is around the corner from the Folies-Bergere theatre and not far from the Paris shopping district that includes the famed headquarters of Galeries Lafayette.

Paris Mayor Anne Hidalgo extended a “message of affection and solidarity” to the victims. She said many residents and tourists had been evacuated from neighbouring buildings and hotels and Paris authorities were helping to provide them temporary accommodations.

Authorities said about 200 firefighters and police were involved in the operation.

Firefighters and police evacuated people from the damaged buildings and dozens of fire trucks raced to contain the blaze.

Several people were led down from upper floors on ladders pushed up on the outside of the building by firefighters.

A helicopter evacuated the wounded. Silver-helmeted firefighters and red firetrucks filled the street and inspected adjoining courtyards.

Pedro Goncalves, an employee at the Hotel Mercure opposite the bakery, said he saw firefighters enter the bakery in the morning but he and his co-workers “thought maybe it’s a joke, a false alarm,” and they went back to work. About an hour later, he said a blast rocked the surrounding streets, one so powerful that he felt a whistling in his ears.

“I heard one big explosion and then a lot of pressure came at me, a lot of black smoke and glass,” he said. “I had just enough time to get down and cover myself and protect my head.” Mr Goncalves, who was struck by shattered glass, had cuts on his head and spots of blood on his sweater and undershirt.

He ran for the exit and then went back to check on the hotel’s clients, adding that some of them had head injuries and were bleeding. He said the hotel was “destroyed” in the blast. “Thank God I’m OK,” he said.

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

He said that as he approached the scene, a woman was crying for help from the first floor of a building: “Help us, help us, we have a child”.

“I was sleeping and woke up by the blast wave,” Claire Sallavuard, who lives on the Rue de Trevise where the explosion occurred, told AFP.

“All the windows in the apartment exploded, doors were blown off their hinges, I had to walk on the door to leave the room, all the kids were panicking, they couldn’t get out of their room,” she said.

Rescuers eventually used a ladder to evacuate the family, who lived on the first floor.

Another witness told The Associated Press that she was awakened by the blast and feared it was another terrorist attack.

The blast rattled an already apprehensive city, which was on lockdown across the CBD due to the weekly violent protests by the gilet jaunes, or “yellow jackets’’ who are seeking to unseat French President Emmanuel Macron.

Authorities said 32,000 protesters took to the streets across the country.