inside corcoran, our producers saw violence erupt many times. though never between inmates and officers. as we neared the end of our stay, no one foresaw that the greatest threat to corcoran staff might come from an event in a california prison more than 100 miles away. >> three guards and two inmates were taken to area hospitals this afternoon after a stabbing in the maximum security area. two inmates used homemade weapons to stab two sergeants and a correctional officer around 1:00 this afternoon. >> it's significant enough that we lock down statewide the whole system. we made the determination that it had to do with a gang activity and southern hispanic gangs. in this particular case, the attacks seemed unprovoked. so that gave us cause to wonder about how widespread this might be. staff being assaulted and attacked is extremely serious. and we need to take all