A power outage late Thursday led to significant delays for Metro’s Blue, Red and Orange line riders and hampered the agency’s ability to communicate what was happening, according to transit officials.

Metro officials said Friday that a UPS, an “uninterruptible power supply,” at the Carmen Turner Facility in Landover malfunctioned.

Engineers are investigating why the UPS, which “governed power for computer systems within the facility,” failed, Metro chief spokesman Dan Stessel said. The UPS is part of the backup-power system, he said, but “we do not have any reason to believe that there was a failure of commercial power.”

The problem began about 11:30 p.m. and came on a night when scheduled track work on the Blue, Red and Orange lines was already creating delays. Metro advised riders to add 25 minutes to their travel times.

Because workers were out on the tracks, Metro officials opted to hold trains at stations during the outage, causing further delays, Stessel said. Trains were held in stations from about 11:55 p.m. until 12:10 a.m., he said.

For some riders, the track work and the power outage combined to create delays of more than 40 minutes.

The first reports of the problem surfaced on Twitter, as riders sent out messages asking whether others were experiencing serious delays and had any idea what has happening. They were met by silence from Metro, which added to the frustration.

Massive delays from Thursday morning’s commute, caused by a broken rail on the western end of the Red Line, were still fresh in many riders’ minds. Metro board members had also met Thursday to discuss holding public hearings about possible fare increases later this year. Riders have complained that paying more doesn’t seem logical when they are frequently faced with equipment failures and delays.

Stessel said the partial power failure at the agency’s rail and bus control center prevented Metro officials from sending e-mail alerts and text messages to riders. Digital displays at all Metro stations were also affected, he added.

Stessel said radio communications were affected briefly.

Power was restored about 12:10 a.m., Metro said.

“We apologize to our customers who were delayed or inconvenienced last night,” Stessel said Friday. “We acknowledge that this was not our finest hour, and we will take the necessary steps to do better in the future.”

Stessel said that the UPS has been placed in “bypass mode” and that Metro “will assign a power technician to provide around-the-clock monitoring of the UPS until a permanent fix is made.”