Nearly half of all federal prisoners infected with coronavirus are in Southern California, with massive outbreaks uncovered at Lompoc and Terminal Island after authorities expanded testing.

As of Friday, there were 823 inmates who tested positive in Lompoc, and another 644 at Terminal Island. In Lompoc two inmates have died, while six at the San Pedro facility have succumbed to the illness, according to the Federal Bureau of Prisons (BOP) website.

Forty staff members have also contracted the disease across both facilities, officials say.

It’s difficult to curb the spread of the virus in settings where people are clustered close together. There are now 3,082 federal inmates infected across the BOP system, resulting in 45 deaths.

The first positive case was identified at Lompoc on March 31. Dozens more were diagnosed in April, but the outbreak’s full extent wasn’t known until after BOP began testing all inmates there this week. That process began at Terminal Island two weeks ago.

The federal agency could not provide specific figures on what percentage of each population had been tested by Friday. On Tuesday, it said 1,000 inmates at Terminal Island had been tested, resulting in 443 positive cases.

“While this represents approximately 42% of the inmate population, only 10% of those tested are exhibiting outward objective symptoms, such as coughing and fever,” according to a news release.

On Thursday, there were 722 confirmed coronavirus cases in Santa Barbara County, including 272 at the Lompoc prison. By Friday, the prison outbreak had surpassed the number of previously known cases countywide, according to its Department of Public Health website.

In Los Angeles County, the epicenter of California’s outbreak, Terminal Island’s infections account for a smaller portion of the nearly 30,300 confirmed cases.

The Lompoc cases fall across two separate lockups, one medium-security and the other low-security. There are about 2,700 people housed between both, while 1,050 are detained at Terminal Island, which houses offender who need long-term medical or mental health care, according to BOP.

A 10-room emergency hospital was completed at Lompoc on Monday, and both facilities have moved hundreds of beds into their decommissioned factories and other areas currently going unused to create space and quarantine sick people. “Field-living quarters” have also been set up on the prison grounds, officials say.

Inmates are also banned from using telephones and email stations in an effort to prevent the virus from spreading via keyboards and handsets. Authorities encourage loved ones to send letters, though many has complained the lag time leaves them worried for days about inmates’ health amid the outbreaks.

Under new BOP protocol, detainees are placed in isolation and tested as soon as they show symptoms. Those who test positive, as well as those who test negative but have symptoms of the respiratory illness, will all be isolated.

Even those who test negative and don’t show symptoms will be subject to two-week quarantine, the federal agency says.