By Robert Mclean

NEW YORK (CNNMoney) -- Delta was hit by a crippling computer outage on Sunday night that disrupted flights around the nation.

It's the second time in less than six months that the U.S. carrier has suffered a major IT problem resulting in delays and angry passengers.

The FAA said late Sunday that there was a nationwide ground stop on all Delta domestic flights but that international flights weren't affected.

"Delta teams are expeditiously working to fix a systems outage that has resulted in departure delays for flights on the ground," the company said in a statement. "Flights in the air remain unaffected."

Upset travelers took to Twitter to vent about the outages.

"@Delta I'm here in Atlanta will they let us know when things start working again?" wrote Twitter user @Indydog63.

The airline said it "apologizes to customers for the inconvenience."

Delta's website and mobile apps were also down, which added to customers' frustrations.

The problems come about a week after United Airlines temporarily grounded domestic mainline flights due to an IT issue.

A previous Delta outage caused travel chaos around the globe.

In August, the airline lost power at its operations center in Atlanta setting off a system failure that resulted in around 2,000 flight cancellations over several days.

After that fiasco, Delta agreed to give affected customers refunds and vouchers for future travel.

-- Tony Marco and Chris Isidore contributed to this article.

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