A nursing home in the Seattle area is at the center of the US coronavirus outbreak

Officials there also say they aren't accepting any more patients and on-site visits from family and friends aren't allowed either.

Four people with ties to the facility have died, making it now the epicenter of the novel coronavirus outbreak in the US. County and federal health investigators are trying to figure out how the virus spread to the facility, and more importantly, how to stop it from killing any more people.

A patient was taken Monday night by ambulance to a hospital, according to a first responder with knowledge of the situation.

CNN has reached out to Life Care Center for comment about the patient. The source said all emergency calls to the facility are being treated as coronavirus.

There have been 18 confirmed cases of novel coronavirus in the state of Washington, and six people have died including the four from the Life Care Center. Those six people ranged in age from their 40s to their 80s.

At least three of them had underlying health conditions.

More than 50 residents and staff have been experiencing symptoms and will be tested for coronavirus, King County health officer Jeffrey Duchin said.

The facility has about 108 residents and 180 staff members, he said.

An investigation into the facility was launched after a resident and a health care worker tested positive for the coronavirus, Duchin said.

"Unfortunately we are now starting to find more cases in Washington state that appear to have been acquired locally and we know the virus is spreading in some communities," Dr. John Wiesman, the state's secretary of health, said.

Dr. Nancy Messonnier, director of CDC's national immunization and respiratory diseases center, said Saturday the disease is hardest on older people and people who are medically fragile, like those who have chronic medical issues.

It is unclear how the Life Care patients contracted the coronavirus.

In a statement, Life Care Executive Director Ellie Basham said they are monitoring residents and workers closely.

"Any resident displaying these symptoms is placed in isolation. Associates are screened prior to beginning work and upon leaving," Basham said.

It's not only the people at Life Care who officials are keeping a close eye on. The city of Kirkland has put 27 firefighters and two police officers in quarantine, city spokeswoman Kellie Stickney said.

"We have also been notified that some of our firefighters in quarantine are demonstrating flu like symptoms," the city said in a news release. One of the firefighters was released Monday.

As a precaution, emergency medical technicians will now wear protective clothing every time they respond to a report of a sick person, even if that individual does not tell them about any coronavirus symptoms, Stickney said.

Washington Gov. Jay Inslee said the US Centers for Disease Control and Prevention has sent 20 people to help out with the investigation.

Life Care manages or operates more than 200 facilities in 28 states. The company, based in Cleveland, Tennessee, was founded in 1970.

King County will buy a motel and use it to put recovering patients in isolation, the county said in a news release.

One technical college said it will be closed Monday and Tuesday to clean and disinfect the campus. The announcement comes a few days after 16 nursing students and a teacher went to Life Care for a visit.

The first case of coronavirus reported in the United States was a man from nearby Snohomish County.

He arrived at Seattle-Tacoma International Airport on January 15, before any health screenings for the novel coronavirus began at US airports. He was returning from Wuhan, China. The man sought medical care on January 19 after four days of self-quarantine at home, Washington officials said.