CALIPATRIA, Calif. (AP) -- Two inmates were shot and a dozen others injured as guards used pepper spray and gunfire Tuesday to break up a brawl among about 120 inmates at a Southern California prison, authorities said.

Calipatria State Prison remained on lockdown some six hours after the violence broke out among the general prison population, spokesman Lt. Jorge Santana said.

Ten inmates were taken to outside hospitals with injuries ranging from moderate to serious, Santana said. He said all the inmates were expected to survive, but one of the gunshot victims had to be airlifted to a hospital.

Guards used pepper spray on prisoners, then fired four rounds from a Ruger Mini-14 shotgun. Two of the rounds hit prisoners, Santana said.

No staff members were hurt.

Prison officials said the facility with about 4,000 men some 120 miles northeast of San Diego near the Salton Sea has not seen a significant disturbance for some time.

"We were just commenting on how quiet it has been," Santana said. "Something of this magnitude, it's been a few years.

He offered no details on what caused the brawl.

But he said the California Department of Corrections and Rehabilitation, the Office of Inspector General's Bureau of Independent Review and the Imperial County District Attorney's Office will all investigate the incident as required by law.