French officials vowed to inspect all Marseille buildings "unsuitable" for habitation as a fifth body was recovered under rubble of the dilapidated buildings.
The collapse has highlighted concerns over the condition of up to 6,000 buildings in Marseille, which have been estimated to be in similarly poor fix.
Image of buildings on Google Street View before they collapsed, showed that one had five stories and the other six. In total, according to the authorities, 5 to 8 people might have been buried under the rubble. Firefighters are continuing to search for survivors and hope air pockets will keep them alive as they dig.
Authorities said they were looking into what caused the collapse of the buildings, described by residents of the area as dilapidated and in need of fix.More news: Ocasio-Cortez becomes youngest woman elected to Congress
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Minister Christophe Castaner told lawmakers in Paris that he had ordered a building by building audit before an "ambitious programme for ensuring safe conditions" along with Marseille authorities.
"Nearly 6,000 properties have been identified as at risk" in the city, he said, representing some 44,000 lodgings in lower-class neighbourhoods.
The others were so dilapidated they had been condemned and were boarded up, though locals said they were frequently used by squatters. He added that the figures had changed little since making Marseille the European city with "the most decaying housing".
People had been living in nine of the 10 apartments at number 65, while a shop occupied the ground floor. "It is the houses of poor people that collapse - and that is no coincidence", he was quoted as saying by local media.
But a 2015 government report said about 100,000 Marseille residents were living in housing that was risky to their health or security.