It is believed the two people who were found dead in the car were from Crewkerne and Taunton in Somerset.
Avon and Somerset Police have issued the following statement
The car was discovered around 6.30pm yesterday evening.
Crews who were sent to investigate the collapse of the tunnel discovered a vehicle buried under earth and mud.
The road has been closed and a cordon has been put in place while the emergency services attempt to excavate the vehicle.