Power has been restored at Denver International Airport after an “incident” caused certain areas to be without power on Wednesday, including the trains, officials said via social media.

The airport experienced a “power incident” around 9:20 a.m., according to an X post, leaving some areas of the airport without power for almost two hours. Officials posted on X at 11:04 a.m., “power has been restored.”

A news release from the airport said that while some of the airport’s power was restored quickly, some critical areas of the airport — including the trains to the concourse — were without power for roughly an hour.

Because of the power outage, a temporary ground stop was issued by the Federal Aviation Administration at about 10:15 a.m., which was lifted at about 11:35 a.m.

Power was restored at about 11 a.m. Airport operations were back to normal by about noon, after pictures on social media showed the train platforms jam-packed with people.

Airport officials said the outage originated from and was isolated to a single Xcel Energy substation, according to the news release. Xcel is working to determine the root cause of the outage, which could take several days.

“Xcel Energy crews were in the process of energizing a new transformer at a substation that serves Denver International Airport when a piece of equipment shut off, causing the substation to lose power,” a spokesperson told The Denver Gazette via email. “Crews worked quickly and safely and were able to restore power within 45 minutes.”

DIA CEO Phil Washington said in the release that the airport “continues to explore alternative energy solutions” to meet the airport’s growing energy needs.

The outage came during a Department of Homeland Security shutdown that was already causing long delays at many airports as TSA employees worked without pay and during a busy spring break travel week.

A power outage in early February also halted the airport’s train system. That outage was due to a failed transformer at an Xcel substation, which spread to other substations.