SAN DIEGO — Two motorists suffered serious injuries Wednesday morning when the first driver was ejected from his car in a rollover crash on Interstate 8 in the Mission Valley area and the second driver was struck by a vehicle on the side of the highway while checking on the injured motorist.

The first crash was reported around 4:35 a.m. on westbound I-8 just east of Interstate 805, California Highway Patrol Officer Jim Bettencourt said.

A witness told officers that a Honda Accord was traveling at roughly 90 mph just before it crashed, according to a CHP.

The Honda driver was ejected from the vehicle onto the side of the road and an SUV driver stopped to help, but the good Samaritan was struck by another car as he went to check on the injured Honda driver, according to authorities.

Both drivers were taken to a hospital for treatment of serious injuries, Bettencourt said.

No details about the victims or the vehicle that struck the SUV driver were immediately available, but that vehicle's driver remained at the scene.

Authorities shut down the left three lanes of westbound I-8 before reopening all lanes by 5:45 a.m.