An apartment building blaze early Thursday killed seven people in the southern French city of Nice and police were investigating the fire as a possible arson, authorities said.

The dead include three children -- 5, 7 and 10 years old -- and a 17-year-old teenager who tried to escape by jumping from a window, they said.

The apartment was occupied by a family believed to have Comoran origins, the regional prefect Hugues Moutouh said, referring to the southern African island nation.

Ten people were inside when the fire broke out.

Rescuers were alerted at around 2:30 am to the blaze on the seventh floor of the building in the low-income neighbourhood of Les Moulins, known for being a drug-dealing hub, in the west of the city.

In spite of the substantial resources deployed, "unfortunately seven people died during this fire", firefighters said.

Interior Minister Gerald Darmanin said on social media that the quick arrival of firefighters "probably prevented more deaths".