DuPAGE COUNTY, Ill. — 22 cases of COVID-19 have been confirmed at a DuPage County nursing home.

Illinois Gov. JB Pritzker made the announcement Tuesday at a news conference.

Over the weekend, health officials announced a resident at the Chateau Nursing and Rehabilitation Center, located in the 7000 block of South Madison Street in Willowbrook tested positive for COVID-19. That person was hospitalized in critical condition.

The state health department tested others in the same home and 22 cases of the virus were confirmed.

18 residents and 4 staff members are in isolation.

Their conditions are unknown, but health officials said they’re monitoring them closely.

“This is deeply troubling. I was very upset to hear the news from the briefing earlier,” Dan Cronin, DuPage County Board Chairman said. “Our hearts go out to the residents and staff at the long-term care facility who were just diagnosed in the last day.”

About 200 people at the facility underwent testing.

The number of positive cases could climb because health officials haven’t received all the results yet.

“We don’t know how it was contracted but we do appreciate the quick action of the clinical staff at the nursing home,” executive director DuPage County Health Dept Karen Ayala said. “And we feel it was because of their quick action both in diagnosing as well as providing the preventative measures.”

The health department is reaching out to everyone those patients have been in contact with.

“This is part of the way we do disease investigation,” Ayala said. “We start then peeling back and so each of the individuals that these 22 people have come in contact with will now be tracked and identified and asked about how they’re feeling. We’ll start monitoring them as well.”

Health officials say for every person who’s tested positive, they’ve been in contact with an average of 90 people.

“We recommend that they stay at home. That they self quarantine and that they reach out for medical care when and if they develop symptoms,” Ayala said. “We don’t recommend taking public health action for individuals who are contacts of the contacts.”

“We must double down,” Cronin said. “We must intensify our efforts to adhere to the public health guidelines and ask every person to take individual action that they can, they must.”

Health officials said they have been in contact with their counterparts in Washington state in an effort to use them as a resource as they work through these cases.