The novel coronavirus known as COVID-19 has infected a third New York-based employee at CBS News, the network announced in a staff memo on Thursday.

The alarming revelation comes a day after CBS News President Susan Zirinsky wrote to employees that two of their colleagues—one at the 60 Minutes offices at 555 West 57th Street, and the other on the fifth floor of the CBS News production center across the street—had tested positive, and that the entire building would be evacuated and shut down.

“We have now a third confirmed case of an employee testing positive for the virus,” revealed Zirinsky’s latest memo, a copy of which was obtained by The Daily Beast. “That person had been working with the other two employees who had previously tested positive. Each person has provided a detailed list of everyone they have come into contact with over the last few weeks. [HR chief] Jose Andino and his team continue to reach out to all of those named who came into direct contact with our three employees.”

Zirinsky and other key staffers are working from home. Various CBS News programs, notably CBS This Morning, are being broadcast from the news division’s D.C. bureau, where Zirinsky built a new studio for the Norah O’Donnell-anchored CBS Evening News.