A Lodi man, 21-year-old Michael Montgomery, was in custody late Thursday on suspicion of murder, police said. They were still searching for at least two additional suspects and the weapon used in the stabbing, Newman said.

Denver attended Wednesday night's game with his father Robert Preece, who works as a security guard at Dodger Stadium, as well as his brother and his father's girlfriend. The group left after the eighth inning, before the game ended in a 6-4 Giants win, and went to a nearby bar or restaurant, Newman said.

At 11:39 p.m. Denver and his family encountered a group of four or five people, who had not attended the game, as the group left another establishment near Third and Harrison streets, Newman said. They exchanged words stemming from the Giants-Dodgers rivalry.

"It started out as a verbal confrontation and moved to a physical confrontation," Newman said.

Both groups began walking away from that initial fight, "but one of the groups, and it's unclear which group, couldn't let the confrontation go," Newman said.

At some point, Denver realized he had been stabbed, she said. He was taken to San Francisco General Hospital, where he succumbed to his injuries.

Newman said it was too early to determine whether alcohol was a factor in the stabbing.

Denver was arrested twice this year in Mendocino County for alcohol-related offenses<NO1><NO>, according to KGO-TV. He was arrested on suspicion of driving under the influence in July, and for public intoxication at the county fair this month.

At the North Main Street plumbing business where Denver was an apprentice, an office manager who answered the phone said Denver's family asked them to stop granting interviews after a deluge of phone calls from reporters.

The manager, who gave her first name as Gypsy, said Denver's workplace and the whole town was heartbroken by the loss.

"We loved him very much. He was part of this family," she said. "Someone can't grow up here without everyone knowing him in town."

Denver graduated from Fort Bragg High School about six years ago. Retired Timberwolves football coach Jack Moyer, who had Denver in several physical education classes, said he was stunned by the news.

"He was just a good kid. He came to class every day, never caused me any problems whatsoever," said Moyer. "He was well liked among his classmates and got along with everybody. It's a shock."

The altercation several blocks from the ballpark is the latest violent confrontation between Dodgers and Giants fans.

In 2003, Giants fan Marc Antenorcruz, 25, was fatally shot by a group of Dodgers fans after a drunken argument at Dodger Stadium.

In 2011, Bryan Stow, a Northern California paramedic and Giants fan, suffered a traumatic brain injury after two men dressed in Dodgers gear attacked him following a game in Los Angeles. The beating sparked outrage and brought stadium security changes around the country.

Stow's family said in a statement that they were "horrified and deeply saddened" by Wednesday's violence. "Our thoughts and prayers go out to the family."

The teams, which moved west in the 1950s — the Dodgers from Brooklyn and the Giants from New York City — are longtime, fierce National League Western Division rivals, and passions tend to run high when the teams play each other.

Fans of both teams expressed a range of emotions as they entered Thursday night's game at AT&T Park.

"I was a little bit scared at first but then I thought tonight will probably be the safest night at this ballpark, so I thought it was still OK to bring my son out to the game," said Clay Brust, a Dodgers fan from Reno, Nev.

Brian Chew, a Giants fan from San Bruno, said the stabbing was unfortunate.

"It seems like the passion that exudes in some fans is really pointed in the wrong direction," Chew said. "We have bigger purposes in life than just orange and black, or blue and white."