Huntsville, TX (KPRC/CNN) - Police in Texas aren't sure what prompted a 10-year-old boy to shoot his sister and then kill himself.
It happened in the small town of Huntsville.
Walker County sheriff's deputies say Coby Tucker opened fire on his sister in her bedroom, and then fatally shot himself.
The childrens' mother was in another room at the time of the shooting, and called 911 when she heard the shots.
Investigators haven't said how Coby got the gun. But they said the family does have a gun safe in the house.
"The ten-year-old gained access to a handgun, she walked into the 15-year-old's room and discharged the weapon multiple times in the direction of his sister," said Det. Gregory Williams.
Deputies say they have never been called out to the Tucker house before.