Police found two other guns hidden in the room as well.
The boy and his three other siblings were removed from the home.
The father had other charges in his past as well.
From an article:
37-year-old Daniel Duggan, of Loudon County, Tennessee bought a .22-caliber Derringer handgun for protection. He hid the loaded, unlocked gun between the mattress and the slats of a bunk bed in his 11-year-old son's bedroom. Wednesday night the boy found the gun and unintentionally shot his mother, Stacy, at point blank range in the back of the head.
Duggan told reporters that the three of them were in the same room when the shot was fired. "I didn't see the gun," Duggan said. "I just saw the flash and I knew what it was. He (Duggan's son) said,'Oh God, I thought it was a fake gun.'"
Stacy was taken to the hospital where she is in serious condition.
Duggan has been arrested and charged with child abuse by neglect for leaving a gun where his son could get access to it. All four children in the home have been taken into Department of Children's Services custody.
Police took three guns out of the child's bedroom.
Both husband and wife have arrest records that include DUIs, drug and theft charges. The couple has also faced child abuse charges in the past. In 2011, Duggan was charged in connection with an automobile accident that left his son with motor skills problems. In another incident, the boy was run over by a lawn mower at his home, losing three of his toes.
The current incident is still under investigation and the sheriff's office said Stacy could face the same child abuse charge.Every gun in the hands of a child must first pass through the hands of an adult.