Updated

Nineteen inmates were injured Wednesday in a series of racially motivated brawls at a county jail where deadly rioting occurred last weekend, authorities said.

Four different fights involving more than 450 black and Hispanic inmates occurred at the Pitchess Detention Center in Castaic, about 40 miles northwest of downtown Los Angeles, sheriff's officials said.

Four inmates were transported to hospitals. Fifteen more were treated at the facility for minor injuries. No sheriff's deputies were hurt.

The fighting began after inmates housed in a group dorm separated along racial lines. The violence was quickly put down, but similar fights occurred in little more than an hour at three more dorms, leading deputies to fire sting balls on inmates to gain control, said sheriff's Sgt. Diane Hecht.

All seven of the county's jails were placed on lockdown after the fights.

Another section of the same detention center was hit with rioting Saturday between Hispanic and black inmates that killed one man and injured more than 100 others. It was followed by two other melees Monday night that caused one minor injury.

Authorities were investigating the cause of Wednesday's disturbance.

In previous incidents, they have alleged that gang leaders outside the jail called Hispanic associates inside and directed them to attack blacks as retaliation for a recent assault in South Los Angeles.

In central California, four inmates were hurt in fighting that began Tuesday at the California Correctional Training Facility in Soledad, forcing 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, said corrections spokesman J.P. Tremblay.