SAN FRANCISCO — The streets of San Francisco were quiet early Sunday, but the city was bracing for possible trouble as fans gathered in hotspots across the city to watch their 49ers take on the Baltimore Ravens in the Super Bowl, officials said.

In the hopes of avoiding the violence that has marred recent victory celebrations in San Francisco, more than 400 officers were on duty, triple the usual number of officers working on a Sunday, police said.

The extra police and additional preparations by officials follow trouble after two recent victory celebrations got out of hand.

After the 49ers won the NFC Championship Game two weeks ago about a dozen people were arrested — mostly for public intoxication.

There were also problems after the San Francisco Giants won the World Series in late October, with a city bus set ablaze, cars being overturned and bonfires being set in trash containers and in city streets. About three-dozen people were arrested after that that victory.

San Francisco officials have been warning that whether the 49ers win or lose that fans should not allow their celebrating over a victory or expressing their sorrow over a loss lead to the destruction of property or other violence.

"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.

Police Chief Greg Suhr, Mayor Ed Lee and Fire Chief Joanne Hayes-White also toured the city's Mission District last week — where much of the trouble took place during the previous victory celebrations — as they tried to reassure business owners that police would do their best to keep things under control.

San Francisco transit officials were also taking steps to avoid a possible disruption in service by detouring some bus routes and canceling 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.