The A38 near Bodmin in Cornwall has been closed in both directions after a serious crash involving two cars.
One person died in the accident, and another's been seriously injured. It happened at around 2.15am.
The dual carriageway at Glynn Valley was shut following the crash while police carry out an investigation.
The collision involved a Saab and a Ford Fiesta. Police had reports that following the collision at least two people were trapped in their vehicle and number of people had suffered serious, possibly life threatening injuries.
Sergeant Olly Tayler from Devon and Cornwall Police told ITV News that all four of the occupants of the two vehicles were taken to Derriford Hospital in Plymouth.
The road closure has caused significant problems for traffic in the area.