Police say an 11-year-old Martinsburg girl threatened her 7-year-old sister with a gun to force the younger child to play with her.

Martinsburg police say the girl also pointed the .38-caliber pistol at her grandmother. The child surrendered the gun after the grandmother made several demands for it.

The weapon wasn't loaded but police believe the girl didn't know that.

The incident occurred Monday evening at the grandmother's residence.

Police said the two girls argued and the 11-year-old then retrieved the gun from her grandmother's bedroom.

She was being held at a juvenile detention center on charges of brandishing a weapon and domestic assault.

The names of the girls and the grandmother weren't being released.