SAN DIEGO - A motorcyclist was fatally injured on state Route 78 when he crashed into a guard rail and plummeted into a gully.

The crash occurred at 1:58 p.m. Sunday, according to San Diego Police officer Dino Delimitros.

"A single motorcyclist was going at a high rate of speed on eastbound Highway 78 when he lost control and hit a guard rail," Delimitros said. "He was pronounced dead at the scene."

A SigAlert, which was expected to last several hours, was issued by the CHP at 2:21 p.m.

Eastbound SR-78 was closed from San Pasqual Road to Bandy Canyon Road. Drivers were being asked to detour to Old Milky Way.

The motorcyclist was not identified.