Three people died and others were left seriously injured when a coach overturned after colliding with a tree on an embankment.
Police said that the coach driver was among those killed and 53 passengers were thought to have been on board.
The vehicle was travelling northbound on the A3 near Hindhead in Surrey at 11.50pm yesterday when it left the road between the Hindhead tunnel and the exit for Thursley. No other vehicles are believed to have been involved.
Three people aboard the 51 seat coach were declared dead at the scene and a fourth passenger was airlifted to Southampton General Hospital with life-changing injuries, Surrey Police said.
Inspector Richard Mallett, speaking at the scene to Daybreak, said that emergency services were embarking on a "delicate operation" to remove bodies from the scene.
The coach is from the Merseyside area and Surrey Police is working with its counterparts at Merseyside Police, as well as with the coach company, to identify the passengers and notify relatives.
Passengers are being taken to a rest centre which has been set up nearby by Waverley Council.
The road was closed in both directions shortly after the incident, and Surrey Police , Surrey Fire and Rescue and South East Coast Ambulance Service all attended the scene, along with collision investigators.
Motorists are asked to avoid the area until the road can be reopened.
BREAKING: #A3 Closure to remain in place until *ATLEAST* 12 noon today - expected to be extended into PM.
A casualty bureau number has been set up and people concerned about passengers on board the coach should call 0800 056 0154.