Five people were injured, two of them seriously, in an I-5 wreck at Alicia around 11:30 a.m. Tuesday, Orange County Fire Authority Capt. Marc Stone said.
Traffic lanes were reopened following the four-car accident, which sent four people to the hospital, Stone said.
The California Highway Patrol is now investigating, Stone said. Vehicles have been moved to the right-hand lane, but traffic may still be slow.
Witnesses saw vehicles "fly through the air," according to CHP logs.
The initial report was of a white pickup truck crashing with a Toyota SUV. The truck "flipped multiple times," said CHP logs. Stone confirmed that the truck flipped "at least once."
At 11:49 a.m., CHP reported all southbound traffic stopped starting at Lake Forest Drive.
The fire department blocked the two right lanes and the carpool lane at 11:52 a.m.