WILLOWBROOK, Ill. (CBS) — After 22 people have tested for coronavirus at a nursing home in DuPage County, officials must run tests and interview an estimated 2,000 people from one facility.

Gov. JB Pritzker noted that on Saturday, one of the new cases in Illinois involved a resident of the Chateau Nursing and Rehab Center in Willowbrook.

A state infectious control team came to the facility while taking every precaution, and tested its entire population. As of Tuesday, those tests have revealed 22 new positive cases – 18 residents and four staff members.

All residents are in isolation either in the facility or in a hospital, and all staff are being monitored at home, officials said.

The nursing home itself has been placed on lockdown.

“Our hearts go out to the residents and staff of the long-term care facility who were diagnosed just in the last day,” said DuPage County Board Chairman Dan Cronin. “We are praying for all of those who are ill.”

Cronin emphasized that everyone must double down and intensify their efforts to adhere to public health guidelines.

Karen Ayala, executive director of the DuPage County Department of Public Health, said each of the case often comes with an average of 90 people who might have come into contact with them, “so it’s a large number of individuals that we’ll be reaching out to.”

That means they now must run tests and interview an estimated 2,000 people from one the Chateau Nursing and Rehab Center.

“We are waiting on more test results to come back,” Ayala said. “It could increase.”

As CBS 2’s Jermont Terry reported, what if any actions the nursing home took to keep the virus out were being questioned and investigated Tuesday night – especially after a COVID-19 outbreak weeks earlier at a nursing home in Washington state.

To date, 29 people have died from the virus after it spread throughout the Washington state facility.

In Willowbrook, part of a probe by the Centers for Disease Control and Prevention is what steps, if any, were missed. Health officials from the CDC, state, and county were all contacting the people who may have been exposed.