Two children are in hospital under police protection after three members of their family were shot dead in a car on a road in the French Alps.
One of the children, aged four, spent eight hours cowering under the body of one of three adults, thought to be her parents and grandmother.
The child, apparently on a family camping holiday from Britain, was found by police unhurt shortly before midnight on Wednesday huddled on the floor behind the front seats of the car, hidden under the legs and skirt of one of the dead women.
A second girl of about eight, thought to be her sister, had been found earlier with serious injuries having been shot in the shoulder and severely beaten on the head. The children are in hospital in Grenoble under police guard.
A local cyclist was also found shot dead at the scene on a mountain road near the village of Chevaline, close to the Annecy lake and the Swiss border. Officials said the man just happened to be riding by at the time of the attack.
A source close to the investigation told Reuters the owner of the UK-registered car, who was found dead at the wheel, was Iraqi-born Briton Saad al-Hilli from Surrey, in southern England. The cyclist, a young father, was Sylvain Mollier, officials said.
Another cyclist, a British former air force officer, raised the alarm after coming across the car with its engine still running and the older girl stumbled out from behind it and collapsed at his feet.
Police arrived at the scene at about 4pm on Wednesday, shortly after the attack.
Public prosecutor Eric Maillaud said police had no idea of the motive for the "act of enormous savagery."
The cyclist and two of the adults in the car were killed by gunshots to the head, Mr Maillaud told a news conference in the town of Annecy, southeastern France.
About 15 bullet casings were found at the scene and the weapon may have been an automatic pistol, he added.
The younger girl, too terrified to move or make a sound, went unnoticed for eight hours because investigators did not open the car doors in order not to disturb any evidence pending the arrival of forensic experts from Paris.
They finally opened up the vehicle after a man at the campsite who had met the group alerted police to the fact there was a second girl in the party.