California Highway Patrol investigated a high-speed crash along Highway 101 north of Santa Maria overnight.
The crash happened shortly before midnight near the Highway 166 exit.
CHP confirmed at least one of the vehicles was traveling at a high rate of speed went off the highway and overturned.
It is unclear how the other vehicle became involved. Few details were released as of 5 a.m. Monday.
Fire officials tweeted two patients were involved in the crash and CHP said major injuries were reported.
The highway was cleared and will not impact the morning commute.