A Super Bowl week that had gone so smoothly for the Big Easy suddenly turned bizarre when everyone was watching.

The lights went out on the biggest game of the year.

Just imagine the uproar if Baltimore had lost.

The outage, blamed on an unspecified "abnormality" in the Superdome's power system, was an embarrassment for New Orleans, which was hosting its first Super Bowl since 2002 and was eager to show off how it has been rebuilt since Hurricane Katrina.

Mayor Mitch Landrieu called Sunday night's outage "an unfortunate moment in what has been an otherwise shining Super Bowl week for the city of New Orleans."

He said he expected to receive "a full after-action report from all parties involved" in the coming days.

The Ravens had been cruising along with a 28-6 lead in the game when, without warning, the power to the Superdome suddenly shut down early in the third quarter, plunging parts of the 38-year-old stadium into darkness and leaving TV viewers with no football and no explanation why.

For 34 minutes, the players tried to stay loose, the fans milled about in darkened corridors, and stadium officials scrambled to figure out what went wrong. The Ravens barely hung on for a 34-31 victory over the San Francisco 49ers, needing a goal-line stand in the closing minutes to preserve the championship.

"It really hurt us," Baltimore fullback Vonta Leach said. "We had lot of momentum."

There is sure to be some fallout for the city and the Superdome -- especially since New Orleans plans to bid for the title game in 2018, in conjunction with the 300th anniversary of its founding.

Escalators stopped working and credit-card machines shut down, though auxiliary power kept the playing field and concourses from going totally dark.

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

Most fans seemed to take the outage in stride, even starting up the wave to pass the time.

"So we had to spend 30 minutes in the dark? That was just more time for fans to refill their drinks," said Amanda Black of Columbus, Miss.

The problem occurred shortly after Beyonce put on a halftime show that featured extravagant lighting and video effects.

A joint statement from Entergy New Orleans, which provides power to the stadium, and Superdome operator SMG shed some light on the chain of events, although they weren't sure about the source of the problem. It apparently started at the spot where Entergy feeds power into the stadium's lines.

"A piece of equipment that is designed to monitor electrical load sensed an abnormality in the system," the statement said. "Once the issue was detected, the sensing equipment operated as designed and opened a breaker, causing power to be partially cut to the Superdome in order to isolate the issue. ... Entergy and SMG will continue to investigate the root cause of the abnormality."

The FBI quickly ruled out terrorism, and the New Orleans Fire Department dismissed reports that a fire might have been the cause.

On the CBS broadcast, play-by-play announcers Jim Nantz and Phil Simms went silent. Sideline reporter Steve Tasker announced to viewers a "click of the lights" as the problem. Later, the halftime crew anchored by host James Brown returned to fill the time with football analysis.

"We lost all power up here at the press box level," Nantz said after power was restored. He and Simms were off the air for most of the outage.

The failure occurred shortly after Jacoby Jones returned the opening kickoff of the second half for a 108-yard touchdown, the longest play in Super Bowl history and pushing the Ravens to a commanding lead. But when play resumed, the momentum totally changed.

The Niners scored two straight touchdowns and nearly pulled off a game-winning drive in the closing minutes. They had first down inside the Ravens 10, but Baltimore kept them out of the end zone to preserve the victory.

The blackout, it turned out, became more of a footnote than a spark to what would have been the greatest comeback in Super Bowl history.

"It just took us longer to lose," moaned San Francisco linebacker Ahmad Brooks.

No one could remember anything like this happening in the title game, but it wasn't unprecedented.

Just last season, the Niners endured two power outages during a Monday night game against the Pittsburgh Steelers at Candlestick Park.

"I didn't know what was going on," San Francisco safety Dashon Goldson said. "I just tried to keep my legs warmed up."

The Ravens felt the delay turned what looked like a blowout into a close game. Safety Ed Reed said some of his teammates began to fret as the delay dragged on.

"The bad part is we started talking about it," he said. "Some of the guys were saying, `They're trying to kill our momentum.' I was like, `There's two teams on the field.' But once we started talking about it, it happened. We talked it up."

A few of the Ravens threw footballs around to stay loose. Others took a seat on the bench, or sprawled out on the turf.

"I was a little stiff when I got back out there," Baltimore running back Ray Rice conceded. "I'm just glad we were able to finish the game and be world champions."

Finally, the lights came back on throughout the dome and the game resumed.

"Let's go!" referee Jerome Boger barked to the teams.

Monique Richard, who is from the north shore of Lake Pontchartrain, had tickets in the Superdome's upper deck.

"My exact words on the way over here were, `I hope this goes off without a hitch,' because the city just looked so good, they were doing so well, the weather so good everything was kind of falling into place," she said. "Hopefully, everybody will be understanding."

New Orleans was once a regular in the Super Bowl rotation and hopes to regain that status. The Superdome has undergone $336 million in renovations since Katrina ripped its roof in 2005. Billions have been spent sprucing up downtown, the airport, French Quarter and other areas of the city in the past seven years.

Maybe they forgot one of the basics.

Joked Doug Cook, a Ravens fan from New Orleans: "They didn't pay the light bill."