The incident happened at Redland Middle School, located at 16001 SW 248th Street (pictured right), about 2:40 p.m.
According to Miami-Dade Public Schools spokesman John Schuster, a boy slammed a bullet on the floor. The bullet discharged and grazed another boy's leg.
The injured boy was airlifted to Miami Children's Hospital by Miami-Dade Fire Rescue. His condition wasn't immediately released.