The Ossining Children's Center, located on South Highland Avenue, made the announcement on Facebook following the positive diagnosis.
Howard Milbert, the center's executive director, said on Facebook that he understood the post may have been alarming, but it was the fastest way to get the word out.
"We made the decision to post the information because we needed to get the information to you as quickly as possible," Milbert said. "The health and safety of our families and staff are always our primary concern."
The staff member works in the pre-K program and the School Age program, the school said. Their last day of work was Friday, March 13.
Milbert said each family who has children at the school have been contacted by phone individually to suggests they consult with their doctors regarding the potential exposure.
"Please take every precaution to protect the health of yourselves and the entire community," he added.
The school will be closed through Tuesday, March 31.
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