San Francisco and Los Angeles can agree on one thing. The mayors, police chiefs and baseball owners of the two cities banded together in a statement Sunday condemning fan violence after Thursday’s Opening Day assault that left a Giants fan in a coma.

“This attack is unconscionable behavior that will not be tolerated in either of our ballparks or in either of our cities,” read the statement from mayors Ed Lee of San Francisco and Antonio Villaraigosa of Los Angeles, police chiefs Jeff Godown and Charlie Beck, and Giants managing partner Bill Neukom and Dodgers owner Frank McCourt.

Following the Dodgers’ 2-1 win over the Giants, Giants fan Bryan Stow, 42, of Santa Cruz, was beaten by two men outside Dodger Stadium and reportedly hospitalized with a brain injury. A $10,000 reward has been offered for information leading to the arrests of the suspects.

Today’s statement promised prosecution of those responsible “to the fullest extent of the law.”

“This is a great rivalry between teams competing on the field of play,” the statement read. “That’s where it must stay.”

The officials also offered their sympathies to Stow and his family.

“The best thing that we as a community of baseball fans can do to support Bryan and his family is to rise above this outrageous act and exercise good sportsmanship and mutual respect for each other,” they said.

The Giants and Dodgers begin a three-game series in San Francisco on April 11.

aburack@sfexaminer.com