JACKSONVILLE, Fla. — Flights were delayed when an air traffic control center near Jacksonville, Florida, closed for several hours for extensive cleaning after an employee tested positive for the coronavirus.

Jacksonville International Airport tweeted Wednesday that the Federal Aviation Administration’s flight-control center in Hilliard would be closed “into the evening which may cause extensive delays and/or cancellations.” It advised passengers to check with their airlines regarding delayed flights.

It was the second time this year that this center has been closed for cleaning due to the coronavirus. Overall, the Hilliard facility has had 12 personnel testing positive since June, and the nearby Jacksonville International Airport tower also has had a dozen infections, according to data provided by the FAA.

The FAA data show hundreds of coronavirus infections among air traffic control workers since the pandemic began.