Emergency services are at the scene of a collision involving a motorcyclist and two lorries which has blocked the A37 near Gurney Slade.
Police were called by the ambulance service just after 3pm on Wednesday 16 March.
The male motorbike rider has gone to hospital and officers are currently trying to reach his family.
The A37 is closed between its junctions with the B3139 at Old Down and the B3135 near the Mendip Inn and is not expected to reopen before the evening rush hour.
If you witnessed the collision or have any dashcam or CCTV footage which could help the investigation please call 101 and give the reference 490 of 16 March.