The Washington Air Route Traffic Control Center in Leesburg, which covers 165,000 square miles of airspace in Washington and several nearby states, closed for two hours on Sunday after an employee there reported testing positive for the coronavirus.

The facility temporarily shut down from 11:45 a.m. to 1:45 p.m., causing aircraft around the airspace to be rerouted, the Federal Aviation Administration said in a statement.

Air traffic was handled by alternate facilities. The FAA said it has long had such contingency plans in place in case of emergencies.

Employees at the Leesburg facility have tested positive 13 times since the pandemic was declared, according to the FAA’s website.