A power outage plunged the Superdome into darkness shortly after the third quarter of Super Bowl XLVII began Sunday night, delaying the game by nearly 35 minutes.

With 13 minutes 28 seconds to go in the quarter and the San Francisco 49ers in possession of the football, the television audio feed stopped and lights went out in much of the stadium.

The national broadcast on CBS cut to a commercial while players, coaches and fans inside the domed stadium were left in stunned silence and the NFL was dealt an unexpected embarrassment. Backup lights kept the playing surface dimly lit as players retreated to their respective sidelines, awaiting further instructions, then milled about trying to stay loose.

Power wasn’t fully restored for 34 minutes 55 seconds, a nearly unprecedented break in the action during the sport's biggest game.

Banks of lights gradually returned after the outage began about 8:37 Eastern time in New Orleans. Play resumed at 9:11 Eastern.

“We sincerely apologize for the incident,” Eric Eagan, a Superdome, spokesman said in a written statement.

Neither the Superdome nor the NFL immediately announced what caused the outage. “Stadium authorities are investigating the cause of the power outage,” said a league spokesman. “We will have more information as it becomes available.”

Pop singer Beyonce performed an elaborate set at halftime, a performance that included lights, fireworks and electrical theatrics. Citing police officials, ESPN reported that the problem occurred when electricity for the show caused a surge.

As the outage wore on, players gathered under the faint glow provided by a few lights on the dome's ceiling, passing the time by stretching, jogging down the sideline and tossing footballs. At one point, Ravens safety Ed Reed tried to rouse the restless crowd by running down the sideline for a quick rally. It didn’t last long.

Restless fans kept themselves busy with chants, songs and boos. Some even tried to start the wave.

The Ravens were leading 28-6 at the time, shortly after a 108-yard kickoff return by Jacoby Jones to start the second half, but momentum clearly shifted to the 49ers after play resumed. San Francisco got as close as 31-29 but ultimately fell 34-31.

Advertisers couldn’t have been happy about the power outage, which delayed some of their commercials. But some adapted quickly: Oreo, whose commercial aired early in the game, tweeted out an image of an Oreo that said “You can still dunk in the dark,” while Audi ribbed competitor Mercedes-Benz, whose name is on the Superdome, with a tweet: “Sending some LEDs to the @MBUSA Superdome right now.”

CBS, which showed the game, issued a statement saying that “all commercial commitments during the broadcast are being honored.”

The 49ers had a bit more experience dealing with power outages. Last season, in a “Monday Night Football” game, the lights went out in Candlestick Park, prompting a similar delay in action.

Maura Judkis in Washington contributed to this report.