DELANO (AP) — A guard on duty in the yard of a central California prison was shot by someone outside the facility, and a suspect is still at large, authorities said Tuesday.Between 15 and 20 rounds were fired from a high-caliber weapon Monday evening at North Kern State Prison in Delano, a rural area about 35 miles north of Bakersfield.The officer, who was struck once in the torso, was treated at a hospital for minor injuries and released.“The round penetrated his stab-resistant vest, but the wounds were minor. It just scraped his side,” said California Department of Corrections and Rehabilitation spokeswoman Terry Thornton.The officer’s name was not released. It was not clear if the shots were intentionally fired at the officer, or if he was hit by bullets fired generally at the prison, officials said.Several law enforcement agencies, including a sheriff’s helicopter crew, joined the search for a suspect or suspects.