YUCAIPA, Calif. (KTLA) — A total of 51 residents and six staff members have tested positive for the coronavirus at a California nursing home, and a second resident has died, health officials said Tuesday.

Some results are still pending, but the entire Cedar Mountain Post Acute facility is assumed to be infected, Trudy Raymundo, director of the San Bernardino County Department of Public Health, said in an afternoon news briefing. Countywide, officials reported 183 confirmed COVID-19 cases and four deaths as of Tuesday.

Officials first became aware of the outbreak at the 99-bed facility last Thursday, when an 89-year-old woman who was recently admitted was taken to the hospital with respiratory symptoms, according to Elizabeth Tyler, a spokesperson for Cedar Mountain.

It was only after the woman was hospitalized that she tested positive, Tyler said.

Raymundo said health officials were able to expedite testing so that results were received the same day, and they gave Cedar Mountain guidance that included suspending admissions and discharges.

Another three residents of the nursing home were confirmed positive Friday, and a total of 12 cases were confirmed after test kits were delivered to the facility Saturday. The remainder of the positive results were returned Monday.

Raymundo was unsure how many people currently reside at Cedar Mountain, but she said her department collected about 79 specimens from the home. The source of the exposure there remains under investigation.

Test kits were also dropped off Saturday at a nursing home in Mentone, California, where a resident was exhibiting symptoms of the respiratory illness. But as of Tuesday, there were no confirmed positives at that facility, Raymundo said.

People 65 and older are particularly vulnerable to the deadly virus, especially if they have underlying conditions. Those who live in nursing homes are at a higher risk for severe illness, according to the U.S. Centers for Disease Control and Prevention.

The CDC says senior care facilities should restrict visits, halt volunteer programs, cancel group activities and actively screen all residents.

Cedar Mountain says its staff members are being screened upon arriving at work.

An infection preventionist with the state Department of Public Health has visited the facility to give advice on isolation measures and use of protective gear, Raymundo said.

Yucaipa Mayor David Avila said since the city is a significant retirement community, he’s taking precautionary measures seriously. Fire stations are no longer open to visitors and protective gear is being used in all emergencies, after which all first responders’ equipment is decontaminated.