UPDATE: 11:45 p.m. from Delta Air Lines: Delta flights are departing and a ground stop has been lifted as the airline's IT systems begin to return to normal after a systems outage Sunday night resulted in departure delays and cancellations.

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

Approximately 150 flights have been cancelled tonight with more expected. Not all delays and cancellations are being reflected on Delta systems, including delta.com, the Fly Delta App, airport information screens or through our Reservations agents. Some customers are experiencing delays upon landing, particularly at Delta’s hub airports.

A waiver has been issued for travel scheduled on Jan. 29 and 30, for rebooking by Feb. 3. Unaccompanied minors will not be accepted for flights through noon ET, Monday, January 30.

Earlier story from the AJC:

Delta Air Lines passengers who sent tweets to Delta’s account Sunday night, received a message that technical issues with the IT system were causing delays.

The outage was first reported around 7:15 p.m. when the airline tweeted to customers about the issue.

“We’re experiencing technical issues impacting the operation. Our technical teams are working to resolve this as quickly as possible to minimize the impact to our customers. We apologize for any inconvenience our customers may experience.”

A captain told Channel 2 Action News the outage might last until 8:30 p.m. and could be extensive and just before 9 p.m. said delays would take at least another hour.

Delta spokesman Morgan Durrant said teams are working expeditiously to fix a systems outage that is causing departure delays for flights on the ground.

“Flights in the air remain unaffected,” Durrant said.

Similar problems were reported last August, The Atlanta Journal-Constitution previously reported. The airline apologizes and asks those seeking updates to visit news.delta.com.