The 11-year-old boy was inside his Tennessee mobile home, talking with three girls who were standing outside.

The group included 8-year-old McKayla Dyer and her sister, who was also 11, according to court documents. During the conversation that night, Oct. 3, the boy asked the girls to go get their puppies. The girls declined.

The boy left. When he returned, the documents state, he was carrying a BB gun and 12-gauge shotgun.

He “then announced to the girls that he had guns,” according to court documents. “The victim then laughed at [the boy], and stated that she believed they were not real.

“[The boy] then made certain the gun was loaded, cocked the hammer of the gun, and shot the victim just above the heart at a downward trajectory, from a distance of 3-5 feet from inside his window.”

McKayla fell backward and was later pronounced dead.

Now, months after the fatal October encounter, the boy has been found guilty of first-degree murder and ordered to remain in the custody of the state until his 19th birthday, The Associated Press reported.

“The State of Tennessee should utilize all reasonable resources to determine why [the boy], an 11 year-old child, chose to kill an 8-year-old child, and to treat and rehabilitate him so that this will not happen again,” a juvenile court order states. “A child who commits first-degree murder cannot be willy-nilly turned loose into society.”

The court order was posted by WATE-TV, an ABC affiliate. The shooting occurred in White Pine, Tenn., a town about 40 miles from Knoxville.

The boy is “in desperate need of help, and our society has a great need for [him] to receive it,” the order states. One of the boy’s relatives told WATE that the family is expected to appeal.

The Associated Press reports that Department of Children’s Services officials were working to try to figure out where to put the boy, who had been trained in firearm safety, according to the court order.

“Like any other child who comes into custody, he would need a thorough assessment and evaluation to determine the best placement,” agency spokesman Rob Johnson told the wire service. “At this time, it would likely be at an intensive treatment program at one of our private providers.”

McKayla died in her mother’s arms, according to the court documents.

“She was a precious little girl,” her mother, Latasha Dyer, told ABC affiliate WATE after the shooting. “She was a mommy’s girl. No matter how bad of a mood you were in, she could always make you smile.”

The killing came just two days after a mass school shooting in rural Oregon and rocked the small community of White Pine, Tenn. Jefferson County Sheriff Bud McCoig told The Washington Post at the time that McKayla’s death had taken a toll on his investigators.

“We only get through it by the grace of God,” he said.

Both children — McKayla and her killer — attended White Pine School, which teaches students from kindergarten through eighth grade.

“We remember her smile and her beautiful face,” White Pine Principal Bill Walker recalled. “Our normal has changed.”