King County prosecutors said the five family members initially blamed the murders on his younger brother, with prosecutors believing he went as far as to stage the scene and place the murder weapon on his deceased brother's body.

Prosecutors with five counts of first-degree aggravated murder and first-degree attempted murder. According to court documents, the attempted murder charge has a firearm enhancement, and each of the six charges has a domestic violence designation.

KOMO News is not naming the teen because as of Thursday, he's being tried as a juvenile. The case could be moved to adult court after a judge hears from both the defense and prosecutors.

According to the King County Sheriff's Office, deputies found five family members dead inside their home on the 7700 block of Lake Alice Road Southeast, near the Lake Alice public boat launch, after multiple 911 callers reported a possible shooting.

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The King County Medical Examiner's Office (KCME) as 7-year-old Katheryn Humiston, 9-year-old Joshua Humiston, 13-year-old Benjamin Humiston 43-year-old Mark Humiston and 42-year-old Sarah Humiston.

The KCME report indicated that all five family members died from gunshot wounds inside their home.

An 11-year-old girl escaped the home after being shot and ran to a neighbor’s home for help, according to court documents. The girl was taken to the hospital for her injuries and was discharged Wednesday afternoon.

According to court documents, the 15-year-old called 911 and sounded "out of breath." Documents state the teen said, "he just shot my whole family and committed suicide too."

During the conversation with the 911 operator, he claimed his brother had killed their family and "taken himself out," and that he was currently hiding in the bathroom on the main floor of the home.

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Court documents also revealed the 15-year-old told police that a possible motive for his brother killing everyone was that he'd been caught looking at pornographic videos the night before and was about to get in a lot of trouble.

During the 15-year-old's 911 call, prosecutors said the teen's 11-year-old sister ran to a neighbor's house while wounded with a gunshot wound to her neck. According to court documents, she told her neighbors that all the members of her family were dead and that her 15-year-old brother was the shooter.

Prosecutors said the girl told them she was awakened by gunshots and screaming in her home at approximately 4:50 in the morning. They said that she then saw her brother's face, and he shot her.

The girl said her brother then left the room and began checking the pulse and breathing of her other siblings. Moments later, she told authorities that her brother returned to her room. Fearing that she would be shot again, she said she played dead and held her breath.

Following the neighbor's 911 call, police arrived and took the 15-year-old boy into custody.

Court documents state the 15-year-old's next court appearance will is scheduled to occur at 1:30 p.m. on Oct. 25 at the Clark Child and Family Justice Center.