A man who took hostages at a school complex just south of Paris used a "fake firearm", an official said.
All hostages were released unharmed and a suspect was detained after the Tuesday morning incident.
Patrick Dallennes, a top official in the Val de Marne region, said: "It wasn't a firearm he used but a fake one with gas cartridges ... without the capacity to kill."
He added: "It's made to scare ... but it's not very dangerous. It was a replica and at first it was hard to tell that it was fake."
The drama began as parents dropped their children off at the complex, which was being used as a summer camp.
The alleged hostage-taker was incoherent in his talks with police and his motivations remain unclear.
The complex, which includes nursery and elementary schools, is in the town of Vitry-sur-Seine, a commuter town with residents from a variety of socio-economic classes.
Most hostages, who included children, were freed fairly quickly, police said, though one parent was held for several hours. All were unhurt.
Shortly after releasing the last hostage, the man walked out, said Pierre Dartout, the prefect of the Val-de-Marne region.
In late June, a man took four employees of a bank hostage in Toulouse. Authorities at the time said he appeared to be mentally ill and ranted disjointedly about religious motives. Toulouse is the southern French city that was terrorised by a gunman who police say claimed links to al Qaida and killed three Jewish schoolchildren, a rabbi and three paratroopers. The suspected perpetrator, Mohamed Merah, was killed after a long stand-off with the Raid police.