A spirit of hope and anticipation across San Francisco rapidly deteriorated Sunday to sullen disappointment after the San Francisco 49ers lost to the Baltimore Ravens in the Super Bowl.

In the Mission District, which had been the center of celebrations — and violence — after the San Francisco Giants won the World Series last fall, disappointed fans stumbled out of bars after the 34-31 loss.

"Damn, that's all I have to say," said Niners fan David Mejia, 32, of San Francisco.

As the game drew to an end, dozens of police officers and sheriff's deputies fanned out on foot, motorcycles and patrol cars. A patrol helicopter hovered above, watching for signs of trouble.

The city had braced for possible rowdiness in the wake of the damage caused after the Niners won the NFC Championship Game two weeks ago and the Giants' win in the World Series.

After the NFC Championship Game, about a dozen people were arrested — mostly for public intoxication. When the Giants won the World Series in late October, a city bus was set ablaze, cars were overturned and bonfires were in trash containers and in streets. About three dozen people were arrested.

"We will not tolerate the types of property destruction and violence that took place during the World Series," San Francisco District Attorney George Gascon said Friday.

Despite the large number of people on sidewalks, most appeared to be well-behaved in the Mission District after the game. Police declined to say how many arrests had been made.

"City-wide, everything seemed to be pretty good," Officer Carlos Manfredi said. "We did have a couple of flare-ups in the Mission District but otherwise everyone seemed to be behaving themselves."

Jason Helgerson, a 23-year-old from San Jose who had watched the game at the Elixir Bar, took the loss in stride.

"I think it could have gone either way, except for some of those calls," he said. "Being a 49ers fan, I'm just happy we were in the Super Bowl."

Mayor Ed Lee said in a statement that "although they did not come up with a win, our city is proud of our red & gold hometown team."

City officials took precautions to minimize problems whether or not the Niners would be victorious. They asked bars to be careful with how much alcohol they served.

Police Chief Greg Suhr, Mayor Ed Lee and Fire Chief Joanne Hayes-White also toured the Mission district last week as they tried to reassure business owners that police would do their best to keep things under control.

San Francisco transit officials detoured some bus routes and canceled some of the city's famed cable car service.

On the freeways, the California Highway Patrol also had extra officers on duty, and CHP officials were urging people not to drive if they've had too much to drink.

"Make it a safe and sober Super Bowl Sunday," CHP Sgt. Diana McDermott said. "We want everybody enjoying the game with their family and friends."

On Super Bowl Sunday 2010, the most recent year that collision data was available, nearly 25 percent of the crashes that day were alcohol related, the CHP said.