A major power outage grounded flights at Hartsfield-Jackson Atlanta International Airport Sunday afternoon.

Here are the latest updates:

6:29 pm -- A Delta executive has told 11Alive that the airport is being evacuated and that passengers are being urged to use MARTA.

5:50 pm -- Atlanta fire officials are on scene and have received no official reports of fire or smoke. A spokesperson is aware of tweets about smoke at the airport, but so far nothing has been found.

5:41 pm -- Atlanta Mayor Kasim Reed is preparing a statement on the airport power outage.

5:12 pm - -Delta says it is deplaning aircraft that have not been able to depart due to the power outage.

4:43 -- A friend of 11Alive reporter Natisha Lance says partial power has been restored in the International Terminal via a generator, but none of the monitors are on. She says people are “surprisingly calm” because “no one knows what is going on.” No one has told them anything.

4:31 pm -- Delta has issued a travel waiver for passengers affected by the power outage.

4 pm -- Airport officials say they are still working to restore power at the airport. The ground stop continues, and there is no timetable for when flights will be allowed to resume. The exact cause of the power outage is still under investigation. Many inbound flights to Atlanta are being diverted.

3:53 pm -- Southwest Airline has canceled all flights into and out of Atlanta for the rest of the day.

3:37 pm -- According to the U.S. Customs and Border southeastern division, all international flights heading into Atlanta are being diverted to other airports.

3:22 pm -- The FAA has extended the ground stop to at least 4 pm, and says between 80 to 100 jets are parked on the taxiways, waiting for gates.

RELATED | Videos from inside Atlanta airport's power outage

3:15 pm -- Major airlines are canceling flights at Atlanta's Hartsfield-Jackson International Airport in the aftermath of a major power outage Sunday afternoon.

Southwest Airlines is canceling "all but a handful of international flights," according to an airline spokesperson.

Delta Air Lines says it is aware of the power outage and the flight disruptions are expected. Delta customers are encouraged check the status of their flight via the Fly Delta Mobile App or Delta.com.

Airport officials say the outage occurred at 12:55 p.m., and affects several areas of the airport. The outage was due to an electrical issue at a Georgia Power substation, according to an airport spokesperson who spoke to NBC News.

GALLERY: Power outage at Atlanta airport

11Alive's Faith Abubey was in the North Terminal at the time of the outage, and reports that all power is out there. In speaking to staff at the United Airlines desk, she says she was told that the outage was over the entire airport and that flights were grounded.

11Alive News viewer Frank Mullin sent this image of a darkened terminal at Atlanta's Hartsfield-Jackson International Airport on Sunday afternoon.

Abubey reports that the Plane Train, which connects each of the terminals below ground, is also affected.

Additionally, data service in and around the airport area is affected, limiting cell phone service in that area.

John Creft with Georgia Power indicated at 1:30 pm that there was a power outage at Hartsfield-Jackson, and that repair crews had been dispatched to the airport to work on the problem.

Airport officials said they were aware of the problem and were working to update the situation.

Georgia Power officials have also indicated they are working to alleviate the issue as soon as possible.

The FAA released a statement noting a ground stop for all flights heading to Atlanta from other airports around the nation as a result of the power outage at Hartsfield-Jackson.

The Federal Aviation Administration has put in a ground stop for flights headed to Hartsfield-Jackson Atlanta International Airport due to a power outage affecting the airport terminals. The FAA Tower can operate normally, however, departures are delayed because airport equipment in the terminals is not working. A ground stop means that flights headed to Atlanta are held on the ground at their departure airport.

FAA officials said they will provide an update as new information becomes available.

A ground stop at Hartsfield-Jackson will likely affect flights across the entire nation, due to delays resulting from passengers connecting through Atlanta.

Stay with 11Alive News and 11Alive.com for updates and details as they become available.