23-year-old man fatally shot in Mansfield, suspect in custody.

A 23-year-old man was shot and killed in a Mansfield home in Massachusetts. William O'Brien, 22, has been charged with carrying an illegal firearm and carrying a loaded illegal firearm in connection with the shooting. The victim was already dead when first responders arrived at the scene. The shooting is being investigated as a homicide, but authorities say there is no reason to believe the public is in danger.