Georgia officials say a 14-year-old is in custody after his 77-year-old great-grandmother was stabbed to death with a sword. His grandmother was also wounded in the alleged attack.

Police arrived at the family's home Monday and found the grandmother barricaded inside a room and the great-grandmother on the ground outside, said Douglas County Sheriff Phil Miller.

Authorities said when they arrived, the teen was waving a long sword and had a pellet rifle that he fired, breaking the windows of a patrol car.

Miller told FOX 5 that deputies were aware the boy was firing a pellet gun, and told police not to return fire.

Authorities say a Taser was used to take the teen into custody after a standoff. The grandmother was taken to a hospital for treatment of what officials describe as non-life threatening injuries.

Deputies had been called to the house before in incidents involving the 14-year-old, the station reported. And he has reportedly been taken to a facility for a mental evaluation twice before.

The Associated Press contributed to this report.