A 9-year-old Mississippi boy was accused of killing his 13-year-old sister over a video game argument that sparked Saturday. The incident reportedly took place in Monroe County in northeast Mississippi.

Authorities said Sunday that the boy had a fight with his sister after she refused to give him the video game controller. Monroe County Sheriff Cecil Cantrell said the young boy reached out to a .25 caliber handgun and shot his sister in the back of the head. 

Cantrell added that the bullet penetrated the girl’s brain and she was rushed to the Le Bonheur’s Children’s Hospital in Memphis, Tennessee. Authorities said it remains unclear how the young boy got access to the handgun. An investigation is currently underway into the incident.

"He's just 9. I assume he's seen this on video games or TV," Cantrell told the Clarion Ledger, a local newspaper. "I don't know if he knew exactly what this would do. I can't answer that. I do know it's a tragedy."

Cantrell added he was not sure what charges might be filed in the case because of the age of the accused.

"This is all new ground for us, we've never dealt with a kid shooting a kid at age 9," Cantrell said. "That's why I'm not too fast to say anything because there are juveniles involved. We want to do what's right and we're going to get it right."

This is not the first time that a child got access to a handgun.

In an incident that took place earlier this month, an 8-year-old boy obtained a rifle and repeatedly shot his 4-year-old sister. The young girl was taken to the hospital where she was treated for gunshot wounds. The reason behind the shooting was not immediately clear.

In another horrifying incident that took place last year, a 3-year-old girl shot herself with a gun belonging to her father. In the incident, which took place in Philadelphia, the young child obtained the weapon inside one of the bedrooms of the home, police said at the time. The toddler’s father was arrested and charged with endangering the welfare of a child and recklessly endangering another person.