in prison. as i know it is in many of the communities on the streets where these men come from. >> you give what you want. you give respect, you get respect back. >> you can say the wrong word and that can start a whole big melee. >> when an inmate of any race is deemed to be disrespected, pelican bay's powerful gangs band together by race. the slightest of rifts can trigger an institution-wide race war. >> the level of violence is not, you know, overly extreme at the moment but that can change any day. i can't say that it's on a downhill slide, uphill slide, just takes one thing to trigger it off and it's gone. >> next on "lockup," a look back at one of the worst prison riots in u.s. history. female announcer: get on board for better sleep!