NEW ORLEANS — A power outage at the Superdome interrupted Super Bowl XLVII for 35 minutes, with the 49ers trailing the Baltimore Ravens 28-6.

At about 7:37 p.m. local time and only about two minutes after halftime, the game paused as the 73,000-seat building plunged into darkness.

Philip Allison, a spokesman for Entergy New Orleans, which provides power to the stadium, said power had been flowing into the stadium before the lights failed.

“All of our distribution and transmission feeds going into the Superdome were operating as expected,” Allison said.

The outage appeared to originate in a failure of equipment maintained by stadium staff, he added.

The NFL said stadium officials were investigating the cause, but there was no immediate word of why the power went out.

“We sincerely apologize for the incident,” Superdome spokesman Eric Eagan said.

Since the power came back on, the 49ers have cut the Ravens’ lead to 34-31.

The 49ers have had some experience with power going out at Candlestick on Dec. 19, 2011 during a Monday Night game against the Pittsburgh Steelers.

The Associated Press contributed to this story.