Homicide detectives were summoned to the Springwood Apartments, located at the intersection of Springdale Avenue and Torchlamp Lane in Bel-Ridge, around 5:40 p.m.
The victim, who suffered a single gunshot wound, was pronounced dead at the scene.
According to Officer Shawn McGuire, a spokesman for the St. Louis County Police Department, investigators believe the victim was shot and his car rolled down an embankment and struck the complex.
The victim's name has not been released, pending notification of family members.
Fox 2 News will have more information on this story as it becomes available.