Police said two large groups of teens were fighting in a park Friday evening. When they turned on a woman who tried to break up the fight, her boyfriend, 25, intervened.
Several teens chased the man across the street to Surf City Coin Laundry, where their attack was recorded by surveillance video, police said.
The victim underwent emergency surgery at University of California-Irvine Medical Center, where he remained in critical condition Monday.
Authorities declined to identify the teens because of their ages.
The father of one 15-year-old suspect, a man named Richard, contested the police story.
"The man came trying to stab [my son]" with a screwdriver and a knife, Richard told KTLA 5. "He ran from the man."