* Overhead lights went out across half the stadium
* Cause of power failure being investigated by NFL
The biggest U.S. sports event of the year and parties across the world were interrupted by a 35-minute power outage during the football Super Bowl at the Superdome on Sunday.
New Orleans electric utility Entergy Corp said it was not the cause of the partial loss of power and that the problem was due to an issue with the Superdome's equipment.
National Football League officials said they were investigating the outage and would provide updates as they learned more.
Moments after Baltimore's Jacoby Jones opened the second half with a 108-yard kickoff return for a touchdown that gave the Ravens a 28-6 lead early the third quarter, the scoreboard and half of the overheard lights in the Superdome went out.
Officials waved a stop to play, which abruptly short-circuited the most watched television event of the year.
When the outage began, the overhead lights first went out on the San Francisco 49ers' side of the field before dimming in other parts, although some overhead lighting remained on and kept the 72,968-seat stadium from being plunged into total darkness.
The cause of the delay was initially attributed by TV reports to an outside power feed that had died. Entergy officials said no other parts of New Orleans were affected.
"All of our distribution and transmission feeds going into the Superdome were operating as expected," Entergy spokesman Philip Allison told KACTV in southern Louisiana. The outage appeared to originate in a failure of equipment maintained by stadium staff, he added.
In a statement after the lights came back on, Entergy said they were "working with Superdome personnel to address any outstanding issues."
Superdome spokesman Eric Eagan did not speculate on the cause of the outage, but simply said he was sorry. "We sincerely apologize for the incident," he said in a statement on nfl.com.
The effects were also felt beyond North America, as the Super Bowl, which determines the NFL champion for the 2012 season, is broadcast live in more than 180 countries and in more than 30 different languages.
CBS, the official broadcaster, charged advertisers an estimated $3.7 million to $3.8 million for 30-second spots in this year's Super Bowl.
Last year's NFL title game, in which the New York Giants defeated the New England Patriots, was the most-watched single television program ever in the United States, averaging an estimated 111.3 million viewers.
Super Sunday is the second biggest day for consumption of food and drink for Americans, behind only Thanksgiving Day.
Americans consume an estimated 50 million cases of beer on the day.
With the field only dimly lit, players whiled away the time stretching on the artificial turf, quarterbacks tossed balls around and cheerleaders went through their routines.
When the lights finally came back on, play resumed to the cheers of the Superdome crowd and parties revved back up around the globe.
Outages are rare, but not unheard of, in the NFL. Two power outages in a single game delayed a game between the 49ers and the Pittsburg Steelers at San Francisco's Candlestick Park in December 2011.
The Superdome made headlines around the world in 2005 as a "shelter of last resort" for as many as 30,000 of New Orleans' poorest residents sought refuge there from Hurricane Katrina.
The storm ripped off part of the roof of the stadium, which was restored at a cost of $336 million in several phases. In October 2011, it was renamed the Mercedes-Benz Superdome under a 10-year name sponsorship deal.