Two people are thought to have perished after being buried in their car for more than a week.
The vehicle is thought to have become trapped following a landslide in Dorset caused by heavy rain.
The unnamed man and woman were reported missing from the Avon and Somerset area by their families, and police inquiries traced the pair to the Beaminster area of Dorset on July 7.
This date coincided with heavy rain and a landslide that closed the Beaminster Tunnel.
The fire service has now located a car at the entrance of the tunnel at Beaminster, near Dorchester, Dorset.
An Avon and Somerset Police spokesman said: "Police searching for two people missing from Somerset have recovered a vehicle in Dorset.
"Inquiries into the missing man and woman suggested they were in the Beaminster area on July 7 and Dorset Police were requested to check the area of Beaminster tunnel.
"Dorset Police have found a car under a large volume of earth and mud.
"At this time it is too early to speculate about the outcome but families have been informed and are being supported by family liaison officers."