Monroe County public health commissioner Dr. Michael Mendoza announced eight new confirmed cases of COVID-19 Sunday evening, bringing the local total to 10.
All eight of the people with the new cases were in isolation, the county said. Three of them were hospitalized; the remaining five were quarantined at home.
Mendoza said investigators have begun contact tracing to determine where the new cases originated and whether anyone else was exposed to the infected people while they were contagious.
In details released later Sunday night, the county said four of the eight people had "a clear connection" to the Greece Arcadia Middle School employee who tested positive last week. All four are adults.
Another one of the eight also works in the Greece Central School District, the county said. That person is an employee of Athena High School.
As the number of cases connected to the Greece school district grew, Mendoza recommended that all faculty, staff and families in the district "diligently monitor for symptoms."
Mendoza also said the county was working with district Superintendent Kathleen Graupman to identify people whose risk of infection was highest.
One of the eight people who tested positive also has children enrolled at The Unique Child Day Care Center on Meigs Street in Rochester, according to the county. Mendoza said he has ordered that facility to close for 48 hours.
The county said a firefighter who responded to an emergency call for one of the new cases might have been exposed to the virus.
The firefighter was not symptomatic but was self-quarantining as a precaution, the county said.
The new cases marked a significant spike in local coronavirus activity, after the first case in the county was identified Tuesday, followed by another on Friday.
Erie County also announced new cases Sunday evening, bringing the total there to seven. The Erie County health department had confirmed its first three cases of the virus Sunday morning.
Also on Sunday, Ontario County confirmed its first case of the coronavirus. That person is an employee of a Rochester nursing home, the Monroe County health department said.
The Friendly home, where the person works, said the person is not on the medical team and does not provide direct care. The company said the person sought medical care "immediately upon showing symptoms" and is isolated at home.
None of the four other workers who had direct contact with the person perform clinical services, either, the company said, and all are quarantined at home.
