OAKLAND (CBS SF) — A power outage at the Oakland International Airport terminals was affecting travel Tuesday night, officials confirmed.

The outage occurred shortly after 6:30, according to several travelers on social media.

Attention customers. Currently there is a power outage affecting the airport. OAK staff are working to resolve the issue. Please check with your airline for flight status. Updates to this issue will be made as information is received. — Oakland Intl Airport (@IFlyOAKland) November 27, 2019

Backup generators came on to restore electricity, airport spokesperson Keonnis Taylor said. Power was fully restored to a majority of the terminal complex shortly past 8 p.m., airport officials said.

Security screening was temporarily halted as a result of the outage but has since resumed, Taylor said. Arrivals continued during the outage but some departures were delayed.

“And the power just went out. Black. Like for a few seconds, kinda came back on. They had like a generator and we were just waiting for 30 minutes. Or more than that, like 50 minutes,” explained James Thompson, who was heading to San Diego.

The cause of the outage has not yet been determined.

Two flights that were scheduled to fly into Oakland have been diverted to Mineta San Jose International Airport, according to Rosemary Barns of Mineta San Jose. Both of the flights are from Southwest Airlines–one is from Denver and the other is from Orlando.

Barns also says the San Jose airport’s tower was alerting their flights coming in about a possible thunderstorm. Some flights were also diverted to Sacramento International Airport.

Lines within the Oakland terminals stretched far and were nearly at a standstill as thousands within the airport were waiting.

Mess of holiday travelers at Oakland Int’l airport after a power outage. More on @KPIXtv pic.twitter.com/8GZ3uiGXub — Andria Borba (@AndriaKPIX) November 27, 2019

“Lines are wrapped around the baggage claim. No movement of anything,” Erin Kennedy told KPIX on Twitter.

A passenger told KPIX that they were stuck at Gate 4. “I’m glad they stopped boarding or we’d be stuck on the tarmac,” said Twitter user @BrigidsWisdom.