A prisoner and two guards have been seriously injured after a security van heading to court collided with a lorry and overturned.
The 29-year-old inmate, believed to be a prisoner at HMP Lewes in Sussex, was hurt when the prison van collided with an HGV.
Two escort officers were also taken to hospital with all three of those injured in a serious but stable condition.
Sussex Police said the GEOAmey van was transporting a prisoner on the A27 Lewes bypass road on Monday morning.
Four people were reportedly trapped in the collision, according to East Sussex Fire and Rescue Service.
Aerial pictures showed dozens of firefighters and police working to free the trapped people.
The road was closed in both directions between Ashcombe and Southerham roundabouts and traffic was gridlocked.
A GEOAmey spokesman said: "Following the incident on the A27 in Sussex this morning, the three people on board have been taken to hospital with injuries.
"Two of these are escort officers and the third is a prisoner. The condition of all three is serious but stable."
Sussex Police said rescue and recovery work is continuing at the scene, warning drivers to avoid the area.
A spokesman for the force said: "A man has sustained serious injuries following a road traffic collision on the A27 at the Lewes bypass.
"At 10.55 on Monday, 10 August, police were called to a crash involving an HGV lorry and a security van transporting a prisoner.
"A 29-year-old man is reported to have suffered serious injuries in the collision. Rescue and recovery work continues at the location.
"The road is currently closed in both directions between Ashcombe and Southerham roundabouts.
"Traffic is severely gridlocked in the area and is expected to remain so until later this afternoon."
