A 12-year-old London boy survived being buried under snow for 40 minutes in the French Alps Wednesday after being overwhelmed by an avalanche while skiing with his parents.

“It’s a miracle because he had no victim detection device,” one of the rescuers told Agence France-Presse (AFP). “The chances of survival are tiny after 15 minutes under the snow.”

The boy and his parents were skiing at the La Plagne ski area in southeast France. They had just left a groomed trail to ski an off-piste run when the child was swept away by a 150m by 200m mass of snow that started at an altitude of 2,400 meters.

A rescue dog of the high mountain gendarmerie platoon of Courchevel, arriving on the spot shortly after the accident to search the area for survivors, discovered him conscious about forty minutes later.

The boy escaped with only a broken leg and was transported to the Grenoble hospital, where he was placed under observation.

Reports suggest that a pocket of air had formed under the snow, allowing the boy to breathe, which helps explain his miraculous survival.

French television said that the child and his family were from London and were spending their vacation in Champagny-en-Vanoise.

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