Southwest Airlines apologized to customers after hundreds of flights were canceled.

The airline canceled 518 flights. 1,486 were delayed.

Southwest said the disruptions were due to an intermittent technology issue and ongoing weather challenges.

We are experiencing flight disruptions across our network today due to briefly pausing our service earlier this morning.

We will continue to work with customers who experience a disruption in their travel plans, and we offer our sincere apologies for any interruption.

Southwest didn't respond to Insider's request for comment made outside of normal working hours.

Customers expressed their frustration with the airline, with one saying in a tweet that it was the worst day of traveling he had ever experienced. He said there was zero support.

The airline was accused of using technology issues as an excuse. Stop with the excuses from one customer. This happened a few months ago.

As the airline industry prepares for a busy summer travel season, some of the biggest US air carriers have had difficulty operating.

The flight attendants were told not to refuse assignments. The airline is about to hire 700 new pilots and flight attendants.