(Salem, OR) -- The Oregon State Penitentiary in Salem is on lockdown again, following a fight among inmates. Prison officials say the brawl involved about 20 inmates and broke out around 7:30 last night. Staff members used a chemical spray to defuse the situation. It's the second time in a week the state penitentiary was placed on lockdown. The first time was Monday, after a fight involving about 60 inmates.