In Marseille, a city in southern France, a four-story apartment building was completely destroyed by an explosion. Two bodies have since been discovered.
Six individuals, according to local police, are still missing and rescue operations are ongoing.
The explosion happened in the La Plaine neighborhood on Sunday around 00:49 local time. (23:49 BST on Saturday).
Investigators are investigating into the likelihood of a gas leak even if the source is yet unknown.
Around 200 people had to be evacuated from their houses after the explosion caused minor injuries to five persons from nearby structures. A few hours later, two adjacent buildings partially fell without any further injuries.
On Monday the mayor of Marseille, Benoit Payan, warned nearby buildings were at risk of collapsing.
Around 100 firefighters attended the scene to tackle a blaze that burned under the rubble throughout Sunday.
The fire hampered progress and made it difficult for rescuers to deploy sniffer dogs, although authorities said on Sunday evening that the blaze was showing signs of abating.
The building is believed to have had one apartment on each storey, and city officials said earlier that the people missing included a “young couple”.
Rescue operations continued into the early hours of Monday with the help of a crane and lights.
In a brief statement announcing the discovery of the bodies, the fire department said that “given the difficulties of intervention, the extraction [of the bodies from the site] will take time”.
A local gymnasium and two schools have been opened to accommodate the people who have had to leave their homes. Psychological support is also being offered.
French President Emmanuel Macron said on Twitter that he was “thinking of those affected and their loved ones” and thanked the emergency workers for their efforts.
Mayor of Marseille Benoît Payan said rescuers remained “determined” to find people alive. “Hope must hold us,” he said.