A four-story apartment building fell overnight in downtown Marseille, French media reported Sunday.

According to the French 20 Minutes newspaper, the incident took place shortly after midnight in La Plaine District. No severe casualties were reported, and at least two people were injured.

Eleven people have been evacuated so far, according to the Ouest France newspaper, which detailed that nine of those evacuated, including two children, emerged unharmed.

Payam was quoted later in the day by the BFMTV broadcaster as saying at least five people who had been hospitalized were in need of relatively urgent care.

He also revealed that the fire in the rubble had not yet been put out, hampering search and rescue operations, meaning there could be more victims among the rubble but the authorities have no knowledge of them nor their state.

"There is currently a fire in the rubble of (building) 17. This fire prevents us from sending dogs and teams to search for possible victims that could be under the rubble," he added.

The streets around the building have been cordoned off and choked with dust, with many emergency personnel on site, an AFP photographer said.

Moreover, regional prefect Christophe Mirmand told AFP there were "strong suspicions" that an explosion was behind the collapse, which, in itself, had been possibly caused by a gas leak. "But we must remain very cautious about the causes at this stage."

Officials revealed that they were probing the incident in a bid to clarify the true reason behind the collapse, with accounts saying there were a hundred firefighters on the site. "The priority is to extinguish the fire and clear the rubble to find people possibly underneath it," the commander of the marine firefighters said.

As a safety measure, authorities evacuated other buildings on the street, with residents using a school as shelter until things are clearer.

"It sounded like an explosion," one resident said.

Moreover, the accident put in the limelight the city's housing standards.