Updated at 12:15 p.m. ET
Delta flights around the world were delayed this morning because of a "computer outage," the company says.
A power outage in Atlanta around 2:30 a.m. ET was responsible for the problem, the company said in a statement.
Georgia Power, the electric utility that serves the region, said in a tweet that "Delta experienced an equipment failure overnight," which caused the outage. Delta says it is still investigating what happened.
Flights that were already in the air when the system's problems began were unaffected. For hours, all other flights were grounded.
As of 8:40 a.m., some flights were resuming, Delta says. But "cancellations and delays continue."
"We are aware that flight status systems, including airport screens, are incorrectly showing flights on time," Delta says. Meanwhile, passengers attempting to check in online or through Delta's app have reported seeing error messages.
The problem is "system-wide" and happening "everywhere," the company has said.
"Counter agent says she doesn't know flight status," Delta passenger Lee Lonsberry tweeted. "They're instructed to check everyone in and wish us luck."