Violence broke out at about 8 p.m. Friday night at the Los Padrinos Juvenile Hall in Downey.
According to L.A. County Probation officials, the staff was assaulted by one youth, while another escaped before he was quickly recaptured.
No serious injuries were reported. Downey police said the facility was secured hours later.
"I expect our interim Chief Probation Officer to get to the bottom of what went wrong and make assurances to the Board of Supervisors and the City of Downey that this is not going to happen again," L.A. County Supervisor Janice Hahn said in a statement.
The latest incident came after a gun was found at the facility last week, spurring a day-long lockdown.
The Downey juvenile hall was recently reopened to house some 300 youths transferred from two detention centers — in Sylmar and Lincoln Heights — after regulators found their conditions “unsuitable."
Margarita Perez, assistant chief probation officer, said in May that consolidating the Barry J. Nidorf and Central Juvenile Halls into Los Padrinos will help address staffing, access to treatment and other issues.
But Los Padrinos was itself shut down in 2019 due to security, staffing and other issues, causing families of detained youths to question the transfer.
