Three men believed to be in their late teens and early 20s have been killed after their car and an articulated lorry collided.
A third person was taken to hospital with serious injuries following the crash on the A10 near Turnford, a spokesman for Hertfordshire Police said.
The accident happened on the northbound carriageway at around 2.15pm when a Vauxhall Corsa collided with the Mercedes Artic lorry.
The driver and two passengers in the Corsa died at the scene while a third passenger was taken to the Royal London Hospital, Whitechapel, by air ambulance with serious injuries.
The driver of the lorry was not injured.
More top news
Sergei Lavrov said he hoped the Trump administration would prove more willing to work with Moscow on Syria than the US under Barack Obama.
The funeral of victims' rights campaigner Jill Saward will be held today at Lichfield Cathedral in Staffordshire.
An 18-year-old man has been arrested on suspicion of murder following the death of a teenage girl in the Dinnington area of Rotherham.