Facebook and Amazon have both sent out instructions to their Seattle-based workers to stay at home after the coronavirus outbreak hit their offices. Amazon confirmed Tuesday that a Seattle employee had been diagnosed with COVID-19, and Facebook announced early Thursday that a contractor in its Seattle office has also been infected. “A contractor based in our Stadium East office has been diagnosed with the COVID-19,” a Facebook spokeswoman said in a statement. The spokeswoman added that the location would be closed down entirely until March 9, but employees have been encouraged to work from home until the end of the month. Amazon has issued similar guidance, and The Seattle Times reported Wednesday that Microsoft—which has nearly 54,000 employees in the state—told its employees to stay at home until March 25th. Seattle has the largest concentration of coronavirus cases confirmed to date in the United States, with 39 confirmed cases including ten deaths.