Los Angeles County health officials said Friday they are investigating cases of COVID-19 at 67 institutions countywide, from nursing homes and assisted living facilities to shelters and jails.

That marks more than 40 additional locations since Monday, when L.A. County Health Director Dr. Barbara Ferrer said officials were investigating outbreaks at several nursing homes after three people died at a single facility in Burbank.

At the time, Ferrer said 25 institutions were tied to COVID-19 cases and 11 of them had three or more infections — which she said was considered an outbreak.

On Friday, Ferrer said 11 people from nursing homes or assisted living facilities have died of the virus: “This reflects an additional four deaths since yesterday.”

Nursing homes have been particularly prone to the virus since those most vulnerable to serious infection include adults over 65 and people with underlying conditions. The earliest cluster of COVID-19 deaths in the U.S. was at a nursing home in the Seattle area tied to more than two dozen fatalities.

In Los Angeles County, a total of 321 cases of COVID-19 have surfaced across dozens of institutional settings including “nursing homes, assisted living facilities, shelters, treatment centers, supportive living (facilities), jails and prisons,” Ferrer said.

This includes 25 cases within the county’s correctional facilities including 18 infections among staff and seven among detainees. Ferrer indicated no correctional officers or people in custody have died from the virus.

But crowded jails have been a particular source of concern in efforts to try curbing the spread of the virus. The L.A. County sheriff released at least 1,700 people from custody last month, and state officials said earlier this week another 3,500 inmates statewide will be released to literally make room for social distancing.

In Riverside County, the sheriff’s department is grieving the deaths of two deputies from COVID-19 — one of them likely contracted the illness from an inmate he escorted to Riverside University Health System, Sheriff Chad Bianco said Friday.

Twenty-six employees of the department have tested positive, Bianco said, and most of those infected work at Cois M. Byrd Detention Center in Murrieta. The agency is awaiting test results for another 30 to 40 employees.

As for shelters and treatment centers, Gov. Gavin Newsom announced Friday state officials were working to secure 17,000 hotel and motel rooms for homeless individuals at particularly high risk — adults over 65, those with underlying conditions and people who have tested positive.

Officials have said the initiative will help to ease overcrowding in facilities such as shelters.