LOS ANGELES -- Opening Day at Dodger Stadium turned violent when authorities say two men in Dodgers clothing severely beat a San Francisco Giants fan after Thursday's game. The attack left the victim in critical but stable condition, and authorities asked witnesses for help in identifying the assailants.

Police said the argument started when the two men began taunting three men in Giants gear as thousands of fans left the stadium after the Dodgers' 2-1 win, Detective T.J. Moore said.

The Giants fans tried to distance themselves from their assailants, and two got away from them, but one was struck with fists on the back of the head. As he fell, his head hit the ground in Parking Lot 2 on the third-base side of the ballpark, Moore said.

Both attackers then kicked the victim and ran, Moore said. When the victim's friends turned around to look for him, they saw him on the ground and made their way back to him. Police paramedics on bicycles were the first to arrive to help the victim, who was taken to a nearby hospital, Moore said.

The victim was identified by KGO radio in San Francisco and the Santa Cruz Sentinel as Bryan Stow of Santa Cruz. His brother-in-law, David Collins, told KGO he has "swelling of the brain, a fractured skull and . . . a frontal lobe that's bruised pretty badly."

Stow is a father of two who works as a paramedic for American Medical Response in San Mateo, Collins told the Sentinel. "He's not doing too well," he said. "He's still unconscious and they just decided to put him in a medically induced coma. They are hoping the brain swelling will go down, but it hasn't and they are talking about removing one of his frontal lobes.''

"I was disappointed," new Dodgers manager Don Mattingly said. "You don't want to see that. Everyone likes rivalries, but to me that's crossing the line."

"It's sad," Giants manager Bruce Bochy said. "It's a shame somebody's in critical condition because of a ballgame. When they're out fighting in the parking lot, we've lost sight of what this is all about.''

Investigators reviewed footage of the incident to see if any security camera captured it, but Detective Larry Burcher said so far they'd found "nothing of great value.''

"We're very confident there were witnesses. It happened immediately following the game when everybody was coming out,'' Burcher said.

Moore said no one in the crowd had come forward with any cell phone or video camera footage, but he noted that there were so many people in the area that 90 percent of the crowd may not have even known what was going on.

The Dodgers said they were cooperating with investigators and wished the victim a speedy recovery.

"It is extremely unfortunate that this incident took place on what was otherwise a great day at Dodger Stadium for tens of thousands of fans,'' the team said in a statement. "We're committed to having the most fan- and family-friendly environment in baseball and will continue to make that a top priority.''

The stadium has been plagued by Opening Day violence in the past.

In April 2009, a man stabbed his friend in the stadium parking lot after the home opener, in which the Dodgers beat the Giants, 11-1. Arthur Alvarez was arrested and charged with assault with a deadly weapon. Alvarez, who contended that he was knocked to the ground and acted in self-defense, was acquitted by a jury.

The West Coast rivalry began on April 18, 1958, the first game played in California after both teams moved from New York. The Dodgers beat the Giants, 6-5, in a game played before nearly 79,000 fans at the Los Angeles Memorial Coliseum.

More MLB news