The killings occurred about 12:15 p.m. (1015 GMT) at the gendarmerie station at Malakoff, south of the French capital. Gendarmes carry out policing functions, but under the Defense Ministry. No motive was given.
The officer, whose identity was not made public, fatally shot a superior and then killed his two children, around 10 years of age, before killing himself, Commander Pierre Bouquin said. He said the officer used his personal weapon in the killings.
Interior Minister Michele Alliot-Marie, who served as defense minister in the previous government, rushed to the police station.