Police say a 3-year-old Alabama boy has accidentally shot and killed his 9-year-old sister. Irondale Police Chief Ken Atkinson tells Al.com that the shooting took place Saturday afternoon at their grandparents' house in a Birmingham suburb. He says the boy found a loaded pistol on a bedroom nightstand and shot his sister in the head with it. Atkinson says the incident seems to be a "tragic accident" but an investigation is underway. The girl was flown with life-threatening injuries to Children's of Alabama, where she later died.