At least seven people have been killed and one other is believed to be trapped after an explosion in a four-storey building in Paris.
Sniffer dogs are being used to search for the residential complex in Rosny-sous-Bois, an eastern suburb of the French capital.
Mayor Claude Capillon said: "There's still hope." Gaetan de Raucourt, head of the Paris firefighting department, earlier residents could have found "pockets of air" beneath the rubble.
"People might be sheltering there. We still have hope of finding survivors," he said.
Early indications are that the blast was caused by a gas leak. Among the victims were a 10-year-old boy and another 14-year-old child, emergency services said.
At least 11 others were injured.
Images of the blast showed it had practically ripped in two with the contents of the apartments exposed.
Emergency crew chief Bernard Tourneur said the rest of the building was "threatening to cave in".
Witnesses said the force of the blast shook buildings at least 100 metres from the site.
"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, who lives about 50 metres away from the collapsed building, said she "jumped into her trousers" and rushed to the site, where together with neighbours "we managed to pull two children out".
France's Interior Minister Bernard Cazeneuve visited the scene and pledged support for victims and their families.