What Apalachee High School shooting suspect Colt Gray did before shots fired

New information from the Georgia Bureau of Investigation has revealed what happened before the deadly shooting at Apalachee High School.

In a FAQ posted by the GBI on Thursday, investigators say that 14-year-old Colt Gray brought the "black semi-automatic AR-15 style rifle" to school with him on Sept. 4 in his backpack. While the weapon could not be broken down, officials say the teen was able to hide it in his bag.

Once on campus, authorities say Colt Gray kept the gun hidden until second period. At that time, the GBI reports that Gray "asked a teacher if he could go to the front office and speak to someone."

After getting permission, the GBI reports that the teen took his bag with him and went to the restroom to hide from teachers.

"Later, he took out his rifle, and began shooting," the GBI reports.

By the end of the gunfire, two teachers, 39-year-old Richard Aspinwall and 53-year-old Cristina Irimie, and two students, Mason Schermerhorn and Christian Angulo, both 14, were killed. Nine others were injured.

WATCH: Video: Accused Apalachee High School shooter, father questioned by Jackson County deputies

Colt Gray was apprehended at 10:26 a.m., minutes after the first reports of shots fired were sent to law enforcement. He has been charged with four counts of felony murder, with additional charges pending a grand jury review. His father, Colin Gray, was also arrested for allegedly purchasing the AR-15-style gun used in the shooting, despite knowing his son was troubled and potentially in need of mental health treatment.

Colt Gray, Colin Gray (Barrow County Sheriff's Office)

MORE: Here's what Georgia school shooting suspect's father told FBI in 2023

Speaking to FOX 5's Johnny Edwards, Barrow County Sheriff Jud Smith said that Colt Gray had only attended Apalachee High School for three days before the shooting. 

Smith said whatever past Colt Gray brought with him, he wishes he'd "given Chee Nation a chance."

A FOX 5 Atlanta I-Team investigation revealed Colt Gray’s tumultuous home life. According to police and court records, Colt lived with his father, while his two younger siblings lived with their mother. Last year, Marcee Gray was arrested for damaging her husband's truck. During the arrest, officers found methamphetamines, fentanyl, and a glass pipe in her possession, resulting in a 46-day jail sentence.

Law enforcement sources have confirmed with FOX 5 that Colt Gray was given the weapon used in the shooting as a Christmas gift. His father had purchased the rifle from a store located about six miles from Apalachee High School and five miles from the Gray family’s home.

In a letter obtained by CNN, Marcee Gray apologized to her son's victims, saying, "my son Colt is not a monster."

"To the parents and families of those affected by the tragic events at Apalachee High School, I want to say that I am so sorry from the bottom of my heart," Marcee Gray, the mother of Colt Gray, wrote.

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Colt and Colin Gray remain in custody. Their next hearings are scheduled for December.