SAN DIEGO -- A motorist was killed Thursday when the pickup truck he was driving collided with another vehicle and crashed off Interstate 8 in Mission Valley, authorities reported.

The driver lost control of the 1990 Toyota for unknown reasons while speeding to the west about 7:30 a.m., according to the California Highway Patrol.

The truck swerved to the right and struck the front end of a 2004 Dodge Ram, which in turn crashed into a 1994 Jeep Grand Cherokee, CHP public affairs Officer Brad Baehr said.

The Toyota, meanwhile, careened off the north side of the freeway, went down an embankment and smashed through a chain-link perimeter fence before overturning and coming to rest on its side in a commercial driveway in the 3500 block of Camino del Rio North, Baehr said.

Medics pronounced the driver of the pickup dead at the scene. His name was withheld pending notification of his family.

The other involved drivers were able to safely pull over to the side of the freeway following the collisions and were uninjured, according to Baehr.