A bizarre and mysterious mass murder in the pristine French Alps has gripped the public in both Britain and France.

On Wednesday afternoon, a British cyclist passing near the Saint Jorioz campsite in the Lake Annecy region in eastern France came upon a BMW automobile with the engine still running – he discovered four people inside dead of gunshot wounds.

According to French media reports, the dead comprised a 50-year-old man; an elderly woman; a French cyclist – all shot in the head -- as well as another woman. The cyclist was likely not related to the others found in the car, but a passerby who inadvertently entered into a dangerous scenario.

The British cyclist also saw a young girl, about eight years old, outside the vehicle who had been shot, but barely alive. After contacting local police, the child was flown to a hospital in the city of Grenoble where she is reportedly in stable condition. Kara Owen, the deputy British ambassador to France, visited with her at bedside.

Amazingly, another small child, a girl aged four, survived the shooting and somehow hid in the car for eight hours before police found her. She was reportedly concealed under the body of a dead woman, probably her mother.

She is now in a psychiatric hospital and has spoken briefly with French police.

Police found more than a dozen spent cartridges from an automatic pistol at the locale.

"It was clearly an act of extreme savagery and it was obvious that who did this wanted to kill," Annecy prosecutor Eric Maillaud told reporters.

The identities of the victims -- as well as the motive behind the killings remain a mystery. French media reported that police believe the victims (excluding the cyclist) were members of the same family.

"We do not absolutely know for what reason these people were killed," Maillaud said.

Maillaud noted that Swedish and Iraqi passports were recovered from the horrific scene.

However, the driver of the car has been identified by Agence France Presse as Saad al-Hilli, a 50-year-old Iraqi resident of Claygate, Surrey, just south of London. The dead women are believed to be his wife and mother (or mother-in-law).

Consequently, Surrey police are helping French authorities as well as the UK Foreign and Commonwealth Office (FCO) with the murder probe.

"This is an ongoing investigation being carried out by the French police and we are unable to confirm any details about the incident," the Surrey police said in a statement.

Regarding the four-year old survivor of the brutal attack, Maillaud said: "It was only once we had access to the scene of the crime that we found her. The little girl spoke English. She heard noises, shouts but she can't tell us any more than that… She is being looked after and we are doing everything we possibly can to care for her."

Lake Annecy is extremely popular with tourists, including many travelers from Britain.

Didier Berthollet, the mayor of the nearby hamlet of Chevaline, told a local newspaper: “We have never seen such horror on our doorsteps before. The police have interviewed everyone in the village hoping to find a witness. There are only 70 homes, so it didn’t take them long.”

The Daily Telegraph reported that a source said the massacre was likely not a carjacking gone wrong, although two other attempted carjacking were reported 50 miles away on the same night by an armed gang.

A police source told Europe 1 radio: "Current theories are either that the family were the victims of an armed robbery or that they disturbed a drug deal taking place."