It happened around 10 am Friday at Riverway Sports Park.
Undercover officers happened to be in the area and quickly responded after hearing the gunfire.
They say three cars sped away from the scene.
Officers stopped one of them nearby - but later determined the person inside was a witness.
Detectives soon identified 32-year-old Adam Prideaux as the suspect.
They arrested him at a home on Buena Vista Avenue and also found the gun they believe he used.
Investigators say Prideaux was involved in a fight with the teen before the shooting.
The victim is expected to survive.