Three people died and five others were hospitalized after a chain reaction collision on U.S. Highway 101 just south of Fair Oaks Avenue in Sunnyvale early Monday morning.

All lanes of Highway 101 in both directions were shut down following the 12:28 a.m. collision and remained closed as of 8:15 a.m., according to California Highway Patrol spokesman Officer Ross Lee.

Northbound traffic was diverted onto Lawrence Expressway during the closure. Southbound vehicles were diverted onto N. Mathilda Avenue.

The collision is under investigation. Preliminary information gathered by CHP indicated that a Ford pickup truck traveling north stuck the center divider and became immobilized, blocking some northbound lanes.

Vehicles then collided with the pickup and blocked the northbound lanes.

Three occupants of the vehicles got out and were standing near their vehicles when another vehicle collided with them, causing two to be thrown into the southbound lanes, where another vehicle struck them, according to Lee.

In total, six vehicles were involved in the chain reaction.

All lanes on Highway 101 were reopened around 9:10 a.m.