The fire started at about 10:30 p.m. Saturday at a house in Saint-Quentin, Aisne, LeParisien.fr reported.
The children's father was home at the time of the fire and fled through a first floor window, L'Aisne Nouvelle reported.
He asked a neighbor to "save my children" before he was taken to a hospital by ambulance for treatment of burns.
Several neighbors armed with fire extinguishers broke open a door and entered the burning house, but were forced back out by the flames. Once the fire was put out early Sunday, the bodies of the children were found, police said.
Fire officials said the blaze appeared to be accidental, but an investigation was just beginning.