The Haitian residents of a ground-floor flat in a northern Paris suburb escaped unscathed after a grenade was hurled from the street, the local prefecture said.
The attack took place in a normally quiet area of the Seine-Saint-Denis district northeast of the French capital, a prefecture source said.
The grenade explosion hit the apartment building's hallway as well as the apartment where four Haitian adults and two children were sleeping, but no one was injured.
"There is no link" with the deadly school shooting in the Toulouse area of southern France on Monday in which three children and an adult were killed, the local official said.
An enquiry was launched into the grenade incident.