As of Tuesday, 443 of 1,055 inmates at the Terminal Island Correctional Institution in San Pedro have the virus, along with 10 staff members.
Two inmates have already died of complications related to COVID-19, the Los Angeles Times reported, citing the Federal Bureau of Prisons.
The bureau reports a total of 1,313 inmates and 335 staff nationwide have confirmed positive tests for COVID-19 throughout the system that holds about 153,000 inmates.
Thirty of those inmates had died of coronavirus-related illnesses so far.
Dozens of inmates have been moved into tents in an effort to create social distancing.
Inmates told their families that a military-style medical facility was being erected in the low-security prison yards to cope with the burgeoning number of sick, according to the Los Angeles Times.
Last week, the Terminal Island prison had only 57 inmates who tested positive for COVID-19.
But the number has skyrocketed nearly 700 percent in just seven days, a local TV station, CBSLA, reported.
Terminal Island prison officials said they’ve tested over 1,000 inmates and taken steps to stop the spread of COVID-19, including issuing masks to inmates and staff, according to the CBSLA.