The A30 in Devon is expected to be closed for several hours after a vehicle flipped and landed on its roof.
National Highways said the road had been closed westbound between the A377 near Exeter and the A382 near Whiddon Down following the serious collision involving the vehicle.
Devon and Cornwall Police are on the scene, with collision investigations expected to be carried out throughout the night.
National Highways said the force is in the process of turning traffic caught within the closure around, and advised cars to wait until they are instructed to move.
A diversion is in place, with drivers advised to exit the Alphington Interchange and follow Ide Village Road leading on to Tedburn Road, and rejoin the A30 at Pathfinder Village.
National Highways said in a social media post: “The #A30 in #Devon is CLOSED westbound between the #A377 near #Exeter and the #A382 near #WhiddonDown due to a serious collision involving an overturned van.
“Due to the nature of the incident, the road is likely to be closed throughout the evening.”
The Independent has contacted Devon and Cornwall Police for a statement.
The force told Devon Live: “Police, fire and ambulance are dealing with a serious RTC on the A30 near Pathfinder Village. We were called to the scene at 5.50pm.
“The road is currently closed and traffic is being prevented from getting onto the A30. Single vehicle RTC.
“We are asking members of the public to avoid the area if possible. Congestion is extremely high. We would appeal to any witnesses to contact police on 101 with log number 693 of November 14.”
