SONOMA Co. -- A 25-year-old Vallejo man was seriously injured Friday morning when he was ejected from his vehicle in a rollover crash on Interstate Highway 505 near Allendale in unincorporated Solano County.

The man was allegedly speeding south at 85 to 90 mph in a Mercedes C230 when he rear-ended a Dodge Neon just north of Allendale Road at about 8:25 a.m., according to the California Highway Patrol.

Both drivers lost control and the vehicles traveled to the right edge of the road, where the Mercedes rolled over. Its driver and sole occupant was ejected, and he was flown to the University of California at Davis Medical Center in Sacramento to be treated for major head trauma, the CHP said.

A 21-year-old man in the Neon sustained moderate injuries, and the other two occupants were unharmed, according to the CHP.

Alcohol does not appear to be a factor in the crash.