BOBIGNY, France - Two children and two women were killed on Sunday when an explosion ripped through an apartment building outside Paris, reducing half a residential block to rubble, emergency services said.
A child described as around 10 years old, as well as a boy aged 14 to 18, were among the bodies recovered from the remains of the four-storey building in the northeastern suburb of Rosny-sous-Bois.
"Our house moved, we were trembling from fear," said Pauline, a neighbour who lives 100 metres (yards) from the collapsed building. The explosion, at around 08:00 am (0600 GMT), was so loud that "our ears were ringing," she added.
Others ran out into the street to help victims.
Ghislaine Poletto, 55, who lives about 50 metres away, 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, four of them seriously, while rescue workers continued to comb the site for five people, including a child, who were still unaccounted for.
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 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 were on site, but would not confirm their link to the disaster.
GRDF, the company in charge of delivering gas to homes, told AFP that "no leaks had been reported previously" in the area.
Neighbour Maryline Yyvon suggested otherwise.
"They'd been digging under the sidewalk just in front of the building," she told AFP.
"Given the force of explosion, it wasn't just a gas canister, that's for sure," she said.
Deputy Mayor Serge Deneulin said the building dates to the 1970s and was "in perfect shape".
City officials set up a makeshift shelter in a nearby school with an on-site medical team for families hit by the blast.