Authorities ordered a lockdown at Folsom Prison after a 19-year-old convict from Los Angeles County was wounded in the prison's 38th inmate knifing case of the year. Clayton Mills, serving a 25-year to life term for murder, was in serious condition at University Medial Center in Sacramento. Prison spokesman Lt. T. J. Smith said it was the 12th knife attack in four days. Five of the incidents have resulted in serious injuries. Under lockdown conditions, prisoners stay in their cells and are fed there. They are not allowed out for exercise. Smith said the lockdown would remain in effect while a cell-to-cell search is carried out for prisoner-made knives. Smith said Mills was attacked as inmates were walking back to their cells from breakfast. A guard fired a warning shot to break up the scuffle.