Police in Columbia, S.C., are investigating how an 11-year-old boy got a pistol that they say he accidentally discharged on a school bus. No one was injured in the incident. A school principal later found the gun in a 14-year-old girl’s locker. The boy and girl, who are not related, were arrested at school. The 11-year-old boy had the .32-caliber handgun when he boarded the bus Thursday morning. As students got on the bus, the driver reported hearing a noise. She smelled smoke, but thought it came from a firecracker.