A 40-year-old man has died after crashing on a descent in Richmond Park, London, on Sunday morning.

The man lost control of his bike on a patch of gravel on the descent of Broomfield Hill, according to the London Evening Standard.

Oliver Prior, who witnessed the incident, said that the man fell and hit his head after his wheels slipped on the gravel. No other person or vehicle was involved in the incident, and the man was wearing a helmet.

“We were coming up the hill, and the man was coming down on the outside of the bend where the road has the most amount of gravel. His bike slipped from underneath him and he fell and hit his head,” Prior told the Evening Standard.

A passing doctor put the man into the recovery position. He was taken by air ambulance to the Royal London Hospital but later died.