The bodies of a child described as around 10 years old, a boy aged 14-18 and two women were recovered from the remains of the four-storey building in the northeastern suburb of Rosny-sous-Bois. Two more bodies were found late in the evening as firefighters continued to comb the wreckage, leaving two other people still unaccounted for, Mayor Claude Capillon said.
Neighbours said the blast, which happened at around 2230 IST yesterday, was strong enough to shake buildings some 100 metres away. Early indications were that it was an accidental gas explosion.
"Our house moved, we were trembling from fear," said Pauline, a neighbour, adding that the explosion was so loud that "our ears were ringing".
Ghislaine Poletto, 55, who lives about 50 metres away from the collapsed building, said she "jumped into her trousers" and hurried to the site, where together with neighbours "we managed to pull two children out". One of the children was "protected by a mattress and a board above his head, which saved his life," she said.
Firefighters said 11 people were injured in the explosion, four of them seriously.
Gaetan de Raucourt, head of the Paris firefighting department, said there was still hope that occupants had found "pockets of air" amid the wood and dusty concrete rubble, which was piled a storey high and fanned out into the street. "People might be sheltering there. We still have hope of finding survivors," he said.
Emergency crew chief Bernard Tourneur said the search would continue for at least 24 hours with care, since the remainder of the building left standing "is threatening to cave in".
French Interior Minister Bernard Cazeneuve, who visited the scene, and police initially pointed to a gas leak as a likely cause of the blast. A fire service commander, Gabriel Plus, said gas and electricity works had been ongoing at the site, but would not confirm their link to the disaster.
GRDF, the company in charge of delivering gas to homes, said that "no leaks had been reported previously" in the area.
Neighbour Maryline Yyvon suggested the explosion was indeed the result of a gas leak. "They'd been digging under the sidewalk just in front of the building," she said.