Home video shows the boy talking with authorities shortly after the single shot was fired. The boy told police he just wanted to show the gun to friends when it went off.
No one was hurt, and some students thought it was fireworks.
"I was in my class, and I heard it, and then I told my teacher, and she said it was a gunshot," said student Abigail Mendoza.
Some parents now wonder if their children are safe anywhere.
"It's very scary not knowing what can happen when you are leaving your children at school," said mother Barbers Mendoza.
On the surface, everything seemed back to normal on Wednesday afternoon at Baker Elementary School, but parents' views on the safety of their children have been changed for good.
"My son has a special aid teacher with him, and she wasn't even aware of it," said parent Marie Valenzuela.
El Monte police are now investigating the case. The grandmother of the boy could face charges for leaving the weapon in a place accessible to the child. She apparently left the gun in an unlocked suitcase.
Police said the incident could easily have ended with someone getting hurt. There were about 100 children on the playground during the incident.
The boy is not facing criminal charges at this time.
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