Seven people, including four children, were injured in a traffic accident Sunday afternoon when an ambulance responding to reports of a fatal drive-by shooting was struck by a car on Chicago's South Side, The Chicago Tribune reported.

Authorities said the ambulance was on its way to the scene of the shooting -- where two teenagers and a 20-year-old man were shot -- when it was hit by a car that ran a red light.

Two adults and four children involved in the crash were taken in fair-to-serious condition to Metro South Medical Center in Blue Island and Roseland Community Hospital.

Meanwhile, police said the three victims in the drive-by shooting were walking down the street at around 3:30pm when a white or tan car pulled up and someone inside started shooting.

The 20-year-old, who was shot in the back, was taken to the Advocate Christ Medical Center where he later died.

A 17-year-old boy was taken to the same hospital in serious condition after being shot in the stomach and foot, while a 16-year-old boy was taken to Mount Sinai Hospital in serious condition after being shot in the stomach.

Police are investigating the incident, but say that no one has been taken into custody.