A seven-year-old girl who survived last week's shooting of a British family in the French Alps is out of hospital and left the country on Friday, police said.

Zainab al-Hilli, hospitalised since suffering serious head injuries in the attack which her four-year-old sister Zeena survived by hiding under the skirts of their mother and grandmother, left the hospital at 8:15 am (0615 GMT), police said, without confirming her destination.

The attack on September 6 near the village of Chevaline saw Saad al-Hilli, his wife Iqbal, her mother and Frenchman Sylvain Mollier -- a passing cyclist -- shot dead.

Zainab was put in an induced coma after the attack to allow her to recover.

A British cyclist who discovered the victims said on Thursday the scene resembled the set of a TV crime show.

"It was pretty much what you would imagine a set from (TV crime series) 'CSI Miami' would be like," Brett Martin, a former member of the Royal Air Force, told the BBC.

"There was a lot of blood and heads with bullet holes in them."

He said Zainab was "prone on the road, moaning, sort of semi-conscious" when he stumbled across the scene in a forest area in Annecy.