Police have named three teenagers who were killed when their car was in collision with a lorry.
Ashley Jones, 19, from Canvey Island, and 17-year-olds Harry Ferrand and Jack Boyton, both from Enfield, were pronounced dead at the scene of the crash on the A10 in Hertfordshire on Friday.
All three victims were travelling in a Vauxhall Corsa along with a third 17-year-old boy from Enfield, who is in a critical but stable condition at the Royal London Hospital.
The accident happened at approximately 2.15pm on the northbound A10 between Turnford and Hoddesdon.
The driver of the Mercedes lorry involved in the tragedy was not injured.
Traffic police are appealing for anyone who saw the Corsa shortly before the collision, or witnessed the crash itself, to come forward.
Investigating officer Sergeant Colin Jenkinson, of Hertfordshire Police, said: "This is a tragic incident and our thoughts are with the victims' families at this difficult time.
"We are conducting a thorough investigation into the circumstances of the collision and are appealing for anyone who may have seen the blue Corsa immediately prior to the collision happening to please get in contact.
"I would also be interested to hear from anyone who witnessed the collision or noticed something after it took place. Any information you provide could be crucial to our investigation."
Anyone with information is asked to contact police via the 101 non-emergency number.