Emergency units from the San Ramon Valley Fire Protection District responded to a single-car collision just north of Alcosta Boulevard at about 2:45 a.m. that resulted in an overturned vehicle blocking a right lane of Interstate 680, CHP officer Robert Haven said.
A separate collision about 1,000 feet before the overturned vehicle occurred at about 3:10 a.m. at Alcosta Boulevard and possibly involves two vehicles, Haven said.
Two victims with major injuries were transported to regional trauma centers, one to John Muir Medical Center and another to Eden Medical Center, according to a dispatcher for the fire protection district.
A Sig-alert was issued at 3:30 a.m. and canceled just before 5 a.m.
