Five people were injured and eight are unaccounted for after an explosion flattened an apartment building in the southern French city of Marseille.

The cause of the explosion is not yet known. It destroyed the building shortly after midnight on Sunday, and a neighbouring block of flats partly collapsed a few hours later.

Benoit Payan, the city's mayor, said it was likely that people had died.

Almost 200 people were evacuated from nearby buildings.

More than 100 firefighters were sent to tame the flames that followed the blast. The fire burned throughout most of Sunday, and authorities warned the blaze could continue for hours - although on Sunday evening it showed signs of abating.

The fire hindered the search for the missing people, which the city's prosecutors said included a "young couple" and "people of a certain age."

The intense heat and dust has prevented search dogs from picking through the rubble.

Mr Payan said that "we have to be prepared to have victims", and Interior Minister Gerald Darmanin, who travelled to the city on Sunday, told media he didn't know whether those missing were alive or dead.

Local prosecutor Dominique Laurens confirmed to reporters that eight people "were not responding to phone calls", adding that it was impossible so far to identify the cause of the collapse.

However, authorities have said a gas leak is likely.

'Unlike anything I've ever heard'

One local told French media that they heard an explosion "unlike anything I've ever heard".

Some said they heard the ground shake and that they could smell gas in the air.

Christophe Mirmand, a local authority leader in the Bouches-du-Rhone region, said: "There was no danger notice for this building, and it is not in a neighbourhood identified as having substandard housing."

In 2018, two houses collapsed in rue d'Aubagne, near Marseille's historic port, killing eight people. The disaster exposed the city's long-standing housing problem and shocked France.

On Sunday Mr Payan said that this weekend's incident was not caused by structural problems in buildings and as such has "nothing to do with rue d'Aubagne."(BBC)