32-year-old Latanya Pressley from the 1500 block of Judson Way is in custody for her involvement in this incident.
Pressley is charged with Recklessly Endangering Another Person and Violation of the Uniform Firearms Act.
The incident took place Monday morning at John F. Reynolds Elementary School, located at 24th and Jefferson streets in North Philadelphia.
School officials say the .357 Magnum was loaded and that the boy was showing it off to other students in the lunchroom during breakfast.
Officials say the other students notified school police who retrieved the 7-year-old and ushered him to the office where the gun was recovered and secured.
Officials suspended the student, pending the outcome of the investigation.