Flights were briefly suspended at New York City-area airports Saturday afternoon, as the Federal Aviation Administration moved to respond to an air traffic controller trainee who tested positive for COVID-19.

The trainee works at the FAA’s New York Air Route Traffic Control Center in Ronkonkoma, Long Island, which handles high-altitude flights heading to local and those flying over the region to places like Europe. Once planes get closer to the airport they are heading to, the flights are transferred to the towers at those airports.

Though the trainee had not been at the Ronkonoma facility since Tuesday, once the test came back positive, part of the center had to be cleared out for a deep cleaning. “We have contacted local health authorities and we are developing a plan to quickly sanitize/clean the affected areas,” the FAA said in a statement.

That meant that the flights normally handled by the controllers in that section of the Ronkonoma center had to be shifted to other air traffic controllers. In order to manage the shift, the FAA put a “ground stop” in effect.

A ground stop meant that no new flights could go into or out of the air space, so effectively all flights that were getting ready to leave from JFK, LaGuardia and Newark Liberty were paused for about a half hour, and some flights heading toward the region were turned around.

The stoppage also included Philadelphia’s airport, Teterboro Airport in New Jersey and MacArthur Airport in Islip, Long Island.

A Port Authority spokeswoman said all JFK, LaGuardia and Newark were all back to normal operations by around 3:30 p.m.