About 110 additional flights were canceled Monday following a nationwide systems outage that had already grounded about 170 flights Sunday night, Delta Air Lines said.

"I want to apologize to all of our customers who have been impacted by this frustrating situation," Delta CEO Ed Bastian said in a statement. "This type of disruption is not acceptable to the Delta family, which prides itself on reliability and customer service. I also want to thank our employees who are working tirelessly to accommodate our customers."

Delta information technology systems went down about 6:30 p.m. Sunday, leading to delays and cancellations.

In Twitter posts defending his executive order barring travelers from seven predominantly Muslim countries, a move that sparked protests at airports around the country, President Donald Trump said the Delta outage was one of several things that created “big problems at airports.”

The systems were back to normal shortly after midnight. However, officials warned of additional cancellations.

Delta passengers wait in line at Hartsfield-Jackson International Airport after Delta Air Lines grounded all domestic flights due to automation issues, Sunday, Jan. 29, 2017, in Atlanta. (AP Photo/Branden Camp)

Credit: Branden Camp

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Credit: Branden Camp

Customers traveling Monday are encouraged to check their flight status at delta.com and the Fly Delta App.

A change fee waiver has been issued for customers scheduled to travel Sunday or Monday for rebooking by Feb. 3, Delta said.

Unaccompanied minors will not be accepted for flights through noon.

So far, the latest Delta outage pales in comparison to the last one. A glitch in August caused 2,300 flight cancellations over four days and cost the company about $100 million in lost revenue.