At least 22 law enforcement recruits were to the hospital on Monday morning after the group was struck by a vehicle while they were out for a run in the Los Angeles suburb of Whittier, local authorities said.
The incident took place close to the intersection of Mills Avenue and Telegraph Road at 6:30 am, according to California Highway Patrol.
The recruits were running in the street in four columns closest to the curb when they were hit. Those at the front who saw the vehicle veer toward them were able to get out of the way, but those behind were unable to react in time and were struck by the car.
During a press conference at the scene, Captain Charlie Samson described the incident as a mass casualty event in which the southbound vehicle veered across into the opposing lane before hitting the recruits who were running north on the sidewalk.
The serious injuries inflicted on the runners by the crash range from head trauma to loss of a limb, according to the CHP.
A suspect believed to have been operating the vehicle has been detained by the authorities.