All seven Los Angeles County jails were on lockdown Thursday after another brawl broke out between Hispanic and black inmates, continuing a week of deadly rioting, authorities said. Five racially motivated fights broke out Wednesday, the largest involving about 300 inmates Wednesday night in a dorm at the medium- security North Facility of Pitchess Detention Center in Castaic, about 40 miles northwest of downtown Los Angeles, said sheriff's Sgt. Don Manumaleuna. "Deputies were able to regain control of the facility, and at this time they're investigating the cause of the disturbance," he said. A total of 19 inmates were injured in the fighting Wednesday, one critically, said sheriff's Deputy Bill Spear. The fighting began inside a group dorm, where more than 100 inmate separated themselves along racial lines. That violence was quickly put down, but similar fights broke out at three more dorms, leading deputies to fire sting balls on inmates to gain control, said sheriff's Sgt. Diane Hecht. All seven county jails were placed on lockdown, expected to last through Thursday, Spear said. Another section of the same detention center was the site of rioting Saturday between Hispanic and black inmates that killed one man and injured more than 100 others. That was followed by two jail melees Monday night. Investigators were looking into the cause and timing of Wednesday's fights. Authorities have said they suspect the recent violence was started by gang leaders outside the jail contacting Hispanic associates inside and directing them to attack blacks as retaliation for a recent assault in South Los Angeles. In an interview with The Associated Press, California Corrections Secretary Roderick Q. Hickman said his department has offered to work with sheriff's officials. He said state authorities want to know what's causing the problems there so they don't spill into the statewide prison system. The Los Angeles County jails often feed into the prison system. In Central California, four inmates were hurt in fighting that began Tuesday at the California Correctional Training Facility in Soledad. That uprising prompted authorities to place a prison unit on lockdown Wednesday. The fracas, which involved hundreds of black, Latino and white inmates, was not believed to be connected to the violence in the Los Angeles County jail, corrections spokesman J.P. Tremblay said.