The school and the sheriff's office reportedly say the gun belonged to the grandfather, which means he could face charges of making a firearm accessible to a child.
The six-year-old has been suspended until the school can decide his punishment.
A kindergartner in East Texas headed to school with a loaded gun in his backpack this morning, according to KLTV in Tyler.
The 6-year-old boy brought it on the bus headed for Chandler Elementary. The bus driver and bus monitor overheard the children talking about it and took the pistol away from the boy before the bus got to school.
Administrators in Brownsboro ISD are waiting to see what authorities will do before deciding how to punish the child, KLTV reported.