The driver of a prison van and two inmates are being treated in hospital after the vehicle crashed into the central reservation on a dual carriageway in Devon, police have said.
The van, which had six prisoners on board, crashed on the A38 near the end of the M5 motorway outside Exeter on Wednesday.
Devon and Cornwall Police told the Press Association that the driver was in a serious condition while the prisoners were not thought to be seriously hurt.
"The vehicle was in collision with the central reservation and one lane of the westbound carriageway is closed while emergency crews are in attendance," a spokesman was quoted by the Press Association as saying.
"The driver of the van is said to be in a serious condition and was treated by paramedics at the scene before being taken to the Royal Devon and Exeter Hospital for treatment.
"Two of the prisoners on board were also taken to hospital for treatment, though they are not thought to be seriously injured, while the remaining four were transferred in another vehicle."
One Westbound lane of the A38 was closed at the scene.