In family photos, the young men pose politely in turbans and ties. But in secret snapshots confiscated by police, some of the men reveal a darker side. They stuff assault rifles down their pants, flex their tattooed muscles and flaunt their bare chests. Others point 9mm pistols at each others’ temples and flash gang signs. Police say these 20-somethings belong to three small Indo-American gangs in Alameda and Santa Clara counties the Santa Clara Punjabi Boys, Aim to Kill and the All Indian Mob. Authorities describe their members perhaps as many as 500 mostly Sikh men in Northern California as some of the Bay Area’s most violent offenders. “Their conflicts always result in a stabbing, shooting or beating,” said Dave Lanier, a Fremont police sergeant who also is the region’s foremost expert on Indo-American gangs. Investigators began focusing on the gangs after a series of violent incidents during the past two years. Young men in gangs are particularly troubling for a community that often finds itself portrayed as a “model minority” even though, members say, they wrestle with the same problems most families face. Many in the community downplay the actions of those police identify as gang members, or deny the gangs exist. Some question the motives of the criminal justice system. But others have begun to ask why some educated children from middle-class homes would turn to criminal activities. “The image has been that Indian kids are hardworking, studious types, doing very well,” said Bob Dhillon, a Sikh religious leader in San Jose.