RENO, Nev. (AP) — Students from a shuttered northern Nevada elementary school and their families were being tested for the new coronavirus after the father of one student was diagnosed with the disease, health and school officials said Friday.

“There are no confirmed cases of COVID-19 at that elementary school, but we continue to investigate,” Washoe County Health Manager Kevin Dick told reporters during a news conference describing actions taken since the second case of coronavirus in Nevada was discovered Thursday.

Dick said investigators in northern Nevada were trying to rule out COVID-19 as the “influenza like illness” that has been affecting people at the school.

Health officials in Las Vegas announced the state's first case earlier Thursday.

The coronaviruses has infected more than 100,000 people worldwide and killed at least 3,400, mostly in China, since it was first identified in late 2019. Officials say most cases have been mild.

The Reno school was undergoing what district Superintendent Kristen McNeill called a second “deep cleaning,” and it will be up to the health district to decide if it will open Monday. Other Reno-area schools remain open. The district has 64,000 students and 8,000 staff members, McNeill said.

The father, in his 50s, was on the Grand Princess cruise ship now being held off the coast of California for coronavirus testng. Officials said his condition was stable and he was “self-isolating" at home.

The Las Vegas case involves a man, also in his 50s, who officials said recently returned from a trip to Washington state, where dozens of cases of the virus have been reported. The Southern Nevada Health District said Friday he remained in serious condition. Investigators were monitoring his family members and tracing people who had contact with him since he returned home from trips to Texas and Washington state.

Officials said it appeared both Nevada patients contracted the virus elsewhere, not in the state. Hundreds of people were being monitored statewide, according to a Nevada Division of Public and Behavioral Health website .

The Las Vegas patient did not have symptoms of illness while traveling, “and people in airports or who had limited interactions are not considered close contacts or at high risk," the health district said in a statement.

Potential close contacts include people who share a household, health care providers or people who were within 6 feet of an infected individual for a prolonged period of time, it said, asking those people to self-quarantine for 14 days.