BOSTON (AP) – Flights from airports across the northeast were delayed on Saturday by a computer glitch at an FAA air traffic control facility in Virginia that handles high altitude flights.

Federal Aviation Administration spokesman Jim Peters says the main computer at the Washington “en route” center shut down at about 4:45 p.m. for about 10 minutes.

A backup radar system was used to handle traffic already airborne, but while the computer was down, airports from Virginia to New England were ordered to hold traffic on the ground.

When the system came back, airborne flights were handled before flights on the ground were allowed to take off.

Peters says it was not immediately clear how many flights were delayed. He says nobody was ever in danger.

The incident is being investigated.