(Portland, OR)  --  One man is injured following a shooting in Clackamas.  The Clackamas County Sheriff's Office says the shooting happened last night at Riverside Park on the Clackamas River east of I-205.  Police say two men were arguing when a friend of one of the men intervened and tried to break up the fight, prompting the suspect to shoot him in the leg.  Police arrested 33-year-old Phillip Pierce Jr of Happy Valley on charges of assault and unlawful use of a weapon.