The call came in to police after 11 a.m. Friday from Belmont Charter School in the 4000 block of Brown Street.
Action News is told the incident was initially reported as a child with a gun.
As it turns out, police said, the 10-year-old brought a stun gun to school, after he accidentally grabbed a different bag.
Somebody - police have not said whether it was an adult or another child - noticed the object in the bag and called police.
Officers arrived at the school and investigated for more than an hour.
After talking to the boy's mother, police determined the device was only used for self-defense and had been in that bag for some time.
Neither the child, nor his mother will be charged.
The school was never ordered into lockdown status. No one was injured, and no children were exposed to the Taser.