The boy was arrested.
From an article:
A 16-year-old boy faces charges alleging he fired several shots from a stolen gun during a fight on Monday afternoon in Springfield’s Meadow Park.
Springfield police were called to investigate the incident just after 3:30 p.m. Monday. As many as 10 people from two separate groups may have been involved in the incident, police Sgt. David Lewis said.
No one was struck by any gunfire, and no property damage was reported, Lewis said.
The article doesn't say how or where the gun was stolen.
Every gun in the hands of a child must first pass through the hands of an adult.