(Radio Iowa) – Des Moines police now say the shooting that left a 15-year-old dead was part of an attempted robbery. Police say their investigation has determined the teen who was shot Sunday had a gun and another 15-year-old with a knife was helping him try to rob a 21-year-old man. The man had a gun and shot the teen and he later died. The other 15-year-old is charged with first-degree robbery. Police say they have recovered a gun and are still trying to determine how the three people who have not yet been identified got together.