Police arrested the 15-year-old last night in a park near the family's home at Gading Road and Sheridan Lane.
Investigators also found the weapon, a handgun... They're now looking into who owns it and how the teen got a hold of the gun.
The 36-year-old father is in the hospital with a serious head wound.
Police say it's unclear if the shooting was deliberate an accident or self-defense.