Eight residents of a Southern California nursing home have been hospitalized in a coronavirus outbreak that has infected more than 50 people and killed two of them, a spokeswoman said Wednesday.

Elizabeth Tyler, a spokeswoman for Cedar Mountain Post Acute in Yucaipa, said another two residents of the skilled nursing facility have symptoms but remain on site. The rest of the residents are asymptomatic, she said.

The facility — which provides round-the-clock nursing care some 72 miles east of Los Angeles — doesn’t know how the virus reached its doors and barred visits from family and others more than two weeks ago, she said. It’s possible it came from a woman who arrived at the facility after surgery and stayed five days before returning to the hospital, where she tested positive and later died, she said.

Since the woman tested positive on Thursday, the 99-bed facility has adopted new measures including cleaning rooms and hallways every two hours. Residents’ vital signs are taken every four hours and the facility hired two respiratory therapists and contracted with a pulmonologist, she said.

Six staff members also tested positive for the virus, she said.

Not everyone at the facility was tested as San Bernardino County health officials were running low on test kits, said Lana Culp, a spokeswoman for the county’s public health agency. But with such a large number of positive results, she said everyone is presumed to be exposed.

“Continuing testing for remaining individuals would not add value to the situation since we can assume that the whole facility is exposed,” Culp said in an email.

There were nearly 9,400 coronavirus cases and 200 deaths reported in California as of Wednesday, according to data kept by Johns Hopkins University.

For most people, the virus causes mild or moderate symptoms, such as fever and cough, that clear up in two to three weeks. For some, especially older adults and people with existing health problems, it can cause more severe illness, including pneumonia and death.

The U.S. Centers for Disease Control and Prevention has said that nursing home populations are at the highest risk of being affected by COVID-19 given the “congregate nature” and the fact that many residents have chronic medical conditions. In Washington state, some 35 residents of a single home near Seattle died in an outbreak.

April Verrett, president of Service Employees International Union Local 2015, said her union doesn’t represent workers at the Yucaipa facility. But she said workers at nursing facilities are generally struggling with insufficient personal protective equipment, and she knows of one case where they were encouraged to wear rain ponchos.

“It feels stronger than us in the moment,” she said of the virus.

But it is also hitting a system that has long been strained, she said.

The facility in Yucaipa has an average rating, according to a website run by the U.S. Centers for Medicare & Medicaid Services. In the past three years, six complaints have led to citations — but the number of deficiencies reported at the facility in the past year are a third of the average typically found in California, according to the site.

Since early March, the facility has been screening staff before every shift for signs of the virus with temperature checks, visual observation and questioning, Tyler said.

She said they have sufficient personal protective equipment but are concerned about anxiety in the surrounding community. And residents are also worried, just like everyone else, she said.

“The older you are, and the more health issues you have — the more worried you are,” she said.