A collision involving six vehicles Saturday night in rural Livermore closed State Route 84 near Vallecitos Road and sent three people to the hospital.
Alameda County firefighters and several other agencies responded to an 8:47 p.m. report of the collision, which closed all four lanes for about one hour, according to a department Tweet at 11:12 p.m.
One vehicle set on fire and at least one person was trapped in a separate vehicle, according to fire officials.
Of the three people hospitalized, one was in critical condition and two suffered moderate injuries.
Other agencies responding included the California Highway Patrol, the Livermore-Pleasanton Fire Department and Cal Fire.