A sheriff's deputy was injured early Saturday during a melee between rival gangs that involved six separate fights and an estimated 150 onlookers, authorities said.
The incident outside a Westlake Boulevard restaurant was quelled by 23 law officers, including two California Highway Patrol officers, said Senior Deputy Luis Obregon.
"This is the biggest [such disturbance] I think we've had in a long time," Sgt. Claude Robillard said. "It was like a fever. . . . Sort of like a wildfire getting out of control."
The injured officer, Senior Deputy Tim Cowgill, required treatment for a bruised elbow injured as he tried to break up a fight and corral an intoxicated man, Robillard said.
"He was actually injured by a baton that was being wielded by one of our own people," Robillard said. "One deputy was about to place a strike on the individual and Cowgill's elbow got in the way."
No other injuries were reported.
Four people were arrested for fighting in public, including one unidentified 14-year-old Thousand Oaks youth who was cited and released to his parents. In addition, one other man was arrested for possession of an illegal weapon.
According to Obregon, hostilities began when a Los Angeles-area gang showed up at Cisco's Mexican Restaurant, 925 S. Westlake Blvd., where members of a Thousand Oaks gang had gathered.
Members of the sheriff's Special Enforcement Detail, which focuses on gangs, had the restaurant under surveillance Friday evening because of the gang members' presence. Uniformed officers had made themselves visible by walking through the eatery and patrolling the parking lot, Obregon said.
However, a fight broke out anyway in the restaurant's parking lot about five minutes after midnight. Within moments, five more small fights erupted, drawing what deputies characterized as a "hostile and restless" crowd of about 150 people.
"It didn't matter [that] the officers were there," Robillard said.
Law enforcement officials have been monitoring Cisco's because the eatery has been drawing a younger crowd on weekends, Robillard said.
However, a Cisco's employee who declined to give her name said the incident was the first she knew of at the restaurant.
"This is just a one-time incident," she said. "It's not a normal situation."
Paco Robles, 32, manager of the Westlake Mobil gas station across the street, said he was surprised to hear of the melee.
The neighborhood is "very upscale," he said. "I'm shocked to hear about this brawl. Nothing like that ever happens in Westlake."
The FBI has long rated affluent Thousand Oaks as one of the safest large cities in the nation. In 1994, it was rated as the second-most crime-free urban area in the country with a population of 100,000 or more.
But steadily increasing gang violence in recent years has prompted the creation of numerous Neighborhood Watch groups, and Thousand Oaks has joined a countywide task force aimed at suppressing gang violence.
In addition to the teenage boy, police also took into custody three other Thousand Oaks residents: Dwain Deeder, 21; Reyaldo Pena, 22, and Robert Abarzua, 18. Also arrested was Leonel Fonseca, 22, of North Hollywood.
Because of Thousand Oaks' proximity to Los Angeles County, it is not unusual for gang members who live across the county line to visit the city, Robillard said. But a disturbance on this scale is infrequent.
"It's amazing how things tend to happen around a full moon," he said.