A 77-year-old man was killed Thursday when he was crushed between a horse trailer and the exit gate of his Glen Ellen pasture, police said.

The man, whose name was not released pending notification of relatives, was discovered by a passer-by at 1:21 p.m., according to the CHP.

The man was driving a Dodge Ram truck while towing a large horse trailer on the long gravel driveway of his property off Dunbar Road, the CHP said. Two horses were in the trailer at the time.

As he exited his vehicle to close the gate, the man did not set his parking brake and the truck started traveling backward, CHP Officer Jon Sloat said.

The man was struck by the trailer and then pinned between it and the closed gate. He was pronounced dead at the scene, officers said.