SAN FRANCISCO—The San Francisco 49ers this season have earned a reputation for smash-mouth football. But at the team's NFC championship game against the New York Giants, officials are taking steps to prevent smash-mouth behavior among 49ers fans.

San Francisco police are beefing up security by 25% in the wake of an outbreak of violent incidents at aging Candlestick Park over the past year, said police department spokesman Carlos Manfredi. The crimes range from restroom assaults to parking-lot shootings between rival fans.

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