An armed man took hostages at a school complex just south of Paris this morning, according to French police.
Children were initially among the hostages, but the man now appears to be just holding one adult.
One police official said the man was carrying a gun, others said they did not know what weapon he had.
The police official said officers from the elite Raid force were on site to negotiate with the man.
The man took the hostages in Vitry-sur-Seine, a commuter town with residents from a variety of socio-economic classes.
Another police official said all the children at the complex, which includes nursery and elementary schools, were safe. He added that the adult being held is a parent of one of the children.
French schools have broken up for the summer holidays, but many are running summer activities.
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 whom police say claimed links to al-Qa'ida 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.
The prefect of the Val-de-Marne region said that the officers from the Raid force were in contact with the man in order to negotiate with him.
Pierre Dartout said a parent of one of the children was being held and that homes and buildings around the complex had been evacuated.