Southwest Passengers Urged to Arrive Early After Computer Glitch

Southwest Airlines is urging passengers to arrive at the airport at least two hours prior to departure today, after a spate of computer glitches Sunday.

Systems are "back up and running" this morning, but "technical issues" on Southwest's website, mobile apps, call centers and airport kiosks delayed around 500 flights Sunday, according to the airline, and some of the displaced passengers are still trying to find seats today.

During the malfunction, Southwest employees used "backup systems," including manual tickets, to get passengers to their destinations.

"It's never too early to say thank you and to extend our apologies and we want to share those sentiments both with our hard-working Employees and our loyal and understanding Customers, whom we hope to welcome back for a better experience soon," Southwest said in a statement.

The company declined to specify what caused the glitches.

ABC News' James Scholz contributed to this report.