COLUMBUS, Ohio (WCMH) – Multiple inbound flights to John Glenn Columbus International Airport had to land in other cities Thursday.

Arrival data from FlightRadar24 showed that around 11 flights were diverted, including planes from Denver; Las Vegas; Seattle; Charleston, South Carolina; and New York. The communications director for John Glenn International confirmed at least four of those were due to an issue in the air traffic control tower.

The communications director said around 4 p.m. the tower was shut down because of a reported COVID-19 contamination. FAA protocol is to clear the facility and clean the area. While this was going on, the FAA’s Indianapolis Air Route Traffic Control Center took control for the Columbus branch. That created a slowdown because the center could only handle a certain number of planes.

The FAA’s ARTCCs are regional sites that oversee flights en route to their destinations, and can take over landing services when there is no tower up and running at an airport.

“The center’s role is to provide air traffic control services in the United States for aircraft en-route between airports, and approach and departure control service at airports not served by [instrument flight rules] certified ATC facilities,” the FAA wrote in hiring documents for the Indianapolis ARTCC.

Planes for Southwest Airlines, American Eagle, Delta, Alaska Airlines and Netjets all had to land elsewhere. The last documented diversion on Thursday was an 8:20 p.m. flight from Houston. Aside from some flight delays and one cancellation, all other flights resumed as planned afterward.

This was not the first time that the Columbus tower had to close for COVID-19 decontamination, the communications director said.