Richmond, Va. — A gunman who opened fire minutes after a high school graduation in Richmond, Va., targeted an 18-year-old graduate he had a long-running dispute with, police said Wednesday. Shawn Jackson, 18, and his father, Lorenzo Smith, 36, were both killed Tuesday in the gunfire, which sent hundreds fleeing in panic outside the state capital’s Altria Theater after the graduation ceremony for Huguenot High School. Five other people were wounded by gunfire, and at least 12 more suffered other injuries or were treated for anxiety due to the mayhem, according to police. Richmond Interim Police Chief Rick Edwards said the shooting suspect, Amari Pollard, 19, knew Jackson and the two had been embroiled in a dispute for more than a year. Pollard was arraigned Wednesday morning on two counts of second-degree murder and ordered held without bond.