Immobilized with fear, a four-year-old British girl huddled for eight hours beneath the legs of her slain mother in the back of a car filled with corpses on a remote Alpine road — all while French investigators stood nearby, unaware the girl was there.

The discovery on Thursday of the girl, apparently unharmed, heightened the drama around a mysterious shooting rampage that left four adults dead and a seven-year-old girl hospitalized with bullet wounds and skull fractures.

The reason for the killing, in a wooded area near the village of Chevaline, remains unclear.

All were found in or near a BMW that prosecutors say belonged to a British family vacationing at a campground on the shores of Lake Annecy, a popular retreat in the French Alps. The owners of the campground told investigators the victims included two parents and a grandmother.

A cyclist stumbled across the scene on Wednesday, and police arrived to find a man's body in the front seat and two women in the back, and a dead cyclist with no known ties to the other victims nearby.

Sweden confirmed that one of the victims was Swedish. French authorities found a Swedish passport that appears to be that of an older woman slain in the car, born in 1938, as well as an Iraqi passport.

Iraqi-born driver

The driver of the car was identified as Saad al Hilli, a British citizen from a London suburb who was born in Baghdad in 1962, and the dead biker was identified as Sylvain Mollier, a father of three from nearby Grenoble.

Britain's Sky News cited al Hilli's neighbour George Aicolina as saying that he was an engineer who was "very much in love with his two girls."

The seven-year-old girl, who is the sister of the four-year-old, was discovered near the car beaten with bullet wounds in her shoulder, Annecy prosecutor Eric Maillaud said. She is now in a medically induced coma but her condition is stable, he added.

The bodies were found just before 4 p.m. Wednesday. Although investigators were on the site for hours, the four-year-old girl was only found after midnight.

French authorities struggled to explain why the four-year-old was not discovered earlier and was left for hours alone on the back seat of a car with two corpses, apparently those of her mother and grandmother.

One explanation investigators offered was that the man who discovered the bodies and the rescuers he summoned concentrated their attention on the seven-year-old who had severe injuries.

Maillaud said, "we discovered a little four-year-old girl that no one noticed earlier because she wasn't moving. Probably terrified, she was completely immobile among the bodies."

Maillaud said as soon as investigators opened the door, the girl emerged, smiled and reached out her arms; she was speaking English but couldn't describe what had happened. She was later examined and is well.

"She quickly asked where her family was. We are hoping for more information from her sister that will help the investigators to move forward," he said.

"Firefighters, technicians, doctors looked inside the car through the windows but they didn't see the little girl. The child, terrorized, never moved. She stayed beneath her mother's legs," Lt. Col. Benoit Vinnemann said, according to BFM-TV.

Police at a press conference in Annecy said helicopters using thermal scanners did not detect the 4-year-old in the car, perhaps because her body heat was concealed by the women's bodies she was hiding under.

Britain's ambassador to France Peter Ricketts said British diplomats were trying to reach other family members to have them come to France and support the two girls but that none had yet been located.

Investigators exploring motives

The prosecutor said they were looking at all possible motives, including a score-settling attack or simply that the family was "in the wrong place at the wrong time."

He said police are protecting the girls in case the killers are still on the loose and want to "get rid of" witnesses to the killings.

Ricketts declined to say whether the father's Iraqi ties may have been a factor in the killings.

Three of the four victims were shot in the head, and the fourth victim remains in the car pending further investigation, Maillaud said.

He said the bodies will be autopsied on Friday.

French President Francois Hollande, who met Britain's Prime Minister David Cameron in London on Thursday, promised that French authorities "will do our utmost to find the perpetrators, to find the reasons behind the event."

Cameron said consular staff will do all they can to help the girls and "are working very hard ... to find out what happened in this very tragic case. Obviously the faster we can get to the bottom of what happened, the better."