Police say the shooting happened Saturday morning as firefighters were called to a home on El Camino near Via Robles Drive.
Authorities say the pellet penetrated into his brain and the boy was transported to the hospital where he is currently in intensive care.
Investigators later interviewed residents at the home and determined that an 11-year-old shot the boy while playing in the garage.
The boy's parents were believed to not be at home during the shooting.
"With these type of weapons, things like this happen," said Andrew Diaz with the Coalinga Police Department.
The pellet gun was recovered at the home and police are conducting further interviews to determine whether charges will be filed against the parents.