ANNECY, France — Three of the four people killed in a mystery shooting in the French Alps were shot in the head in what the prosecutor in charge of the case Thursday called an act of "extreme savagery."

The attack, which killed three members of a British-Iraqi family and a passing cyclist, had many of the hallmarks of an assassination carried out by a professional killer.

But the prosecutor Eric Maillaud and Britain's ambassador to France, Peter Ricketts, insisted it was too early to draw any firm conclusions about Wednesday's horrifying events.

"It was clearly an act of extreme savagery and it was obvious that whoever did this wanted to kill," said Maillaud.

Ricketts, whose consular officials are working on the basis that the family were British citizens, added: "This is a terrible tragic event, a brutal murder. We are all asking ourselves these questions and we don't have any answers yet."

"Everything will be done to find the killer or killers," French President Francois Hollande vowed Thursday, as he visited the Paralympic Games in London.

A French police source named the man killed in the car as Saad al-Hilli. In England, neighbors identified his wife as Iqbal and their daughters as Zainab, aged seven, and Zeena, aged four.

Three of the four people killed were found in a British-registered BMW estate car. The fourth victim, a cyclist who arrived at the scene by chance, was named Thursday as local man Sylvain Mollier.

He was shot in the head, as was the driver of the car and the elder of two women who were found in the back seats.

Maillaud revealed that the elder of two young sisters who had survived the shooting had been placed in an induced coma ahead of more surgery at a hospital in Grenoble.

The prosecutor said the girl, thought to be around seven, had been shot in the shoulder and suffered a fractured skull as a result of multiple and "extremely violent" blows to the head during Wednesday's attack.

"Her life is not in danger but obviously she is in no state to be interviewed," he added.

The girl's four-year-old younger sister had survived by crouching beneath her mother's corpse for eight hours, making herself "completely invisible" under the skirt of her mother, said Maillaud.

The fireman and police officers first on the scene, quickly sealed off the scene of the crime, a forest car park near the village of Chevaline. But under orders to leave the car untouched until a forensics team arrived, they failed to spot the girl.

Child psychiatrists in a local hospital were now looking after her.

Police sources have confirmed that the car belonged to Saad al-Hilli, a 50-year-old born in Iraq but resident in Surrey, southeast England.

Neighbors said the older woman, who had a Swedish passport, was his mother-in-law and the other woman, who was carrying an Iraqi passport, was his wife.

The family had been staying since September 3 at the nearby Saint Jorioz camp site, where fellow campers reported their disappearance on Wednesday evening.

Chevaline and the surrounding area on the shores of Lake Annecy is popular with tourists, including many Britons.

It was a veteran of Britain's Royal Air Force who has a second home in the area who discovered the victims, having cycled into the car park at 3:48 pm Wednesday.

The cyclist who was killed had overtaken the veteran just minutes earlier. When he came upon the scene the engine of the BMW was still running.

As the Briton arrived in the car park, the elder girl stumbled towards him before collapsing on to the ground and he alerted emergency services;

That action had probably saved the girl's life, said Maillaud.

The Briton smashed in the window of the driver's seat and turned off the engine before establishing that the three adults in the car were dead.

Several witnesses reported seeing a car speeding away from the scene around the time the attack took place.

Experts from the national police IRCGN unit have collected DNA evidence from the scene and were checking spent bullet cartridges in an attempt to identify the weapon or weapons used.