Flights in and out of New York City were returning to normal Saturday after Delta Air Lines canceled hundreds due to thunderstorms Friday.

A fire at a Federal Aviation Administration technical center in New Jersey also forced the agency to resort to backup communication systems to manage the flow of air traffic across the country, a spokeswoman said. The center's operations were also restored.

The FAA's fly.faa.gov website showed 15-minute delays or less Saturday for flights into and out of New York's LaGuardia and John F. Kennedy airports, and Newark International in New Jersey.

Delta Air Lines, the largest carrier serving Hartsfield-Jackson International Airport, canceled 321 flights in and out of New York, a spokesman said. By Saturday afternoon, flights schedules were returning to normal, spokesman Eric Torbenson said.

“Our recovery from the weather and air traffic control situation is going very well,” the spokesman said in an email. “Minimal cancellations and good progress in the NYC area.”

Southwest Airlines spokeswoman Ashley Dillon also said  operations out of Atlanta are running smoothly with no major delays. Southwest is in the process of merging operations with AirTran, the second-largest carrier serving Hartsfield-Jackson.

An FAA spokeswoman said a fire at its technical center in New Jersey did not compromise any systems used to control air traffic, although weather did affect flights along the East Coast.

"FAA air traffic control systems are now operating normally,” spokeswoman Kathleen Bergen said. “Late Friday evening, the FAA cancelled all ground stops and ground delay programs on the East Coast and in San Francisco that were implemented because of bad weather, including severe thunderstorms in the Northeast.”