Down a winding dirt road in rural White Springs, Fla., four kids were left home alone.

Their parents, 37-year-old Keith Kornegay and 33-year-old Misty Kornegay, had been away since Sunday. Keith, a truck driver, sometimes took his wife with him on runs, leaving the kids with their oldest son, 16-year-old Damien. On Monday, Damien started ranting about being left in charge again.

By the end of the evening, police said, these children would be victims of a chronically troubled home some 70 miles from Jacksonville. Damien’s 15-year-old sister would steal a 9mm handgun from their parents’ locked bedroom while a younger sister stood guard. Then the teenage girl would shoot her brother, police allege, and leave his body sprawled on the living room floor.

“There’s going to be a hundred thousand whys, and we may not ever know exactly why this child acted out like this,” Columbia County Sheriff Mark Hunter said during a news conference. “Life’s very tough, and we get dealt a lot of cards that are unfortunate sometimes.”

Keith Kornegay, left, and Misty Kornegay were arrested on child neglect charges. (EPA/Columbia County Sheriff)

The 15-year-old girl, not named by The Washington Post because the prosecutor has not decided whether to charge her as an adult, told police her brother had beaten her earlier in the day and locked her in her bedroom. She said she had been kept in her room before — about four times per week — with nothing more than a blanket and a bucket to use as a toilet. Her father told police the longest period was 20 days.

On Monday, she was kept there for stealing from her parents’ room, according to a police report cited by the Gainesville Sun. At one point, she asked to be let out to shower. Her brother called their parents and got permission — then he locked her up again.

After he fell asleep Monday evening, police said, the younger sister, 11, let the older girl out and the two allegedly devised a plan.

The 15-year-old allegedly went outside and removed the air conditioning unit from her parents’ bedroom window. She climbed inside, took the gun while her sister stood watch, and loaded it. Then she went to the living room and allegedly fired one shot, killing her brother.

She told police “she went up to Damien and pointed the gun at him and turned her head and pulled the trigger,” the police report said.

“There’s no real rhyme or reason to it,” sheriff’s spokesman Murray Smith told the Gainesville Sun.

After the shooting, the girls went to a nearby Dollar General store, where the 11-year-old phoned a friend’s mother. She said she had run away and needed someone to pick her up, the Associated Press reported. When the woman got there, the older sister told her something might be wrong with another sibling, the report stated. About 10 p.m. local time, the woman alerted police.

“At first we didn’t know what had happened,” Detective Cecil Brownfield told Fox News, “so the officer was very compassionate with the girls. They had put them in the break room at the Dollar General store to keep them comfortable. We were worried about their safety.”

When officers arrived, the teen “would not maintain eye contact and appeared emotionless,” according to the report. Instead, she freshened her makeup as she spoke to police, the AP reported. Soon, she started crying and told police she shot her brother, police said. Although the autopsy has not been completed, Hunter said, investigators suspect the shooting occurred three to four hours before police received the call.

Police rushed to the home. A lawn mower was parked out front. Toys were scattered across the yard. Inside, they found Damien lying on the living room floor and the handgun tossed on a blanket in the hallway.

A 3-year-old sibling was inside the house. The child was turned over to the Florida Department of Children and Families that night.

Hunter said leaving younger siblings in the care of an older child is ordinarily acceptable. But circumstances make this case different.

In the past several years, police have responded to disturbing reports from the home. In 2010, a neighbor called police claiming an uncle had molested one of the girls and filmed sexual acts, the Gainesville Sun reported. The uncle was charged, convicted and sentenced to life in prison. The next year, the children’s mother told police she found the same girl engaging in sexual acts with one of her siblings.

No charges were filed.

After the shooting in Monday, the 11-year-old told police the children rarely had enough to eat. She said “they don’t get much food and it’s usually whatever is left over when her parents are finished eating,” the report stated.

Keith and Misty Kornegay have been charged with child neglect for causing great bodily harm. They face up to 15 years in prison. The girls have been charged with premeditated murder and are being held in juvenile detention up to 30 days.

“Sometimes we can send them home after that, but in light of all of the facts in this case, we don’t have any place to send the children,” prosecutor Jeff Siegmeister told the Gainesville Sun. “I may be forced to actually charge them as adults to hold them in juvenile detention until I can work something out.”