A 15-year-old boy was killed when a convertible sports car was in an accident with a 32-ton tipper truck.
A Hertfordshire Police spokesman said the 17-year-old driver, from Hertford, was seriously hurt in the crash on Sunday.
The sports car hit the lorry, which had been travelling in the opposite direction, after he lost control of the Toyota MR2 on a sweeping bend.
The spokesman said the accident was on Station Road, Stansted Abbots, near the Great Amwell roundabout.
The car was travelling westbound towards the roundabout when the driver lost control.
Head injuries
"The car veered across the carriageway and collided with a Foden 32-ton tipper truck travelling in the opposite direction," the spokesman said.
"The passenger, a 15-year-old boy also from Hertford, tragically died at the scene."
The driver, who has serious head injuries, was initially taken to Princess Alexandra Hospital, Harlow.
He has since been transferred to the Old Church Hospital, Romford, Essex, where his condition is described as critical but stable.
The lorry driver, a 66-year-old man from Essex, suffered minor injuries and was very shaken by the crash, said the spokesman.
Police are appealing for anyone who saw the car before the crash or the collision to contact them.