Georgia Power said it believes a failure of its equipment may have started a fire that led to a massive power outage at Hartsfield-Jackson International Airport causing more than 1,000 flight cancellations Sunday, disrupting flights for travelers from around the world.

"While evaluation of the incident is ongoing, Georgia Power believes that a piece of Georgia Power switchgear located in an underground electrical facility could have failed and started a fire," Georgia Power said in a written statement overnight after the power was restored. "This fire was located adjacent to redundant circuit cables and switching mechanisms serving the airport and those cables were damaged, resulting in the outage and loss of redundant service methods."

Georgia Power said the incident affected the underground facilities as well as substations serving the airport.

“Georgia Power's system responded properly by isolating areas where equipment wasn't operating correctly to ensure safety and minimize damage,” the company said. “No personnel or passengers were in danger at any time.”

In August 2016, a massive system outage at Atlanta-based Delta Air Lines cascaded into thousands of flight cancellations. Shortly after that incident, Georgia Power said the outage was caused by the failure of Delta switchgear equipment, which switches power flows within a system. Delta CEO Ed Bastian also said a power control module at the airline's technology command center failed and caught fire.

That fire and failure cascaded into failures of Delta's flight planning and customer tracking systems. Delta has since taken steps to invest more in technology and backup systems.