A strictly Orthodox boy was believed to have drowned while swimming in a pond on Wednesday.
Thought to be in his mid-to-late teens, the Charedi boy had been swimming at Hampstead Heath in north London during the spell of hot weather.
Eyewitnesses said he had been playing in shallow water in an area not designated for swimming, and was seen calling for help before disappearing under the water.
Emergency teams rushed to the scene, but were unable to locate his body. Helicopters were also used in the search.