The teen charged with opening fire at a Georgia high school denied making prior threats when police interviewed him last year as they looked into online posts threatening a school shooting. Investigators ultimately did not have enough evidence for an arrest, according to an report obtained Thursday.

The 14-year-old suspect, whom authorities have identified as Colt Gray, has been charged as an adult in the shooting Wednesday outside Atlanta that killed four people and wounded nine. He is accused of using an assault-style rifle to kill two students and two teachers in the hallway outside his algebra classroom.

The same teenager was interviewed in May 2023 by a sheriff's investigator from nearby Jackson County who received a tip from the FBI that the boy, then 13, "had possibly threatened to shoot up a middle school tomorrow."

The tip came to the FBI from people in Australia and California who were concerned about comments made by a chat group user on the social media platform Discord, according to a Jackson County sheriff's report obtained by The Associated Press.

The teen was asked about the threat, and told a sheriff's investigator that "he would never say such a thing, even in a joking manner," the report said.

The investigator urged the boy's father to keep his firearms locked away and told him to keep his son out of school "until this matter could be resolved," the report said. The boy's last day before the summer break was a few days before that conversation.

The attack Thursday was the latest among dozens of school shootings across the U.S. in recent years, including especially deadly ones in Newtown, Connecticut; Parkland, Florida; and Uvalde, Texas. The classroom killings have set off fervent debates about gun control and frayed the nerves of parents whose children are growing up accustomed to active-shooter drills. But there has been little change to national gun laws.

Classes were canceled Thursday at Apalachee High School, though some people came to pay respects by leaving flowers around the flagpole and kneeling in the grass with heads bowed. Among them was Linda Carter, who lives nearby. Though she has no children attending the school, Carter said the rampage left her angry and hurting.

"I'm upset, I'm crying constantly," Carter said. "These kids shouldn't have lost their lives. These parents, these adults, these teachers should not have lost their lives yesterday."

When the suspect slipped out of class Wednesday, Lyela Sayarath figured her quiet classmate who recently transferred was skipping school again. But he returned later and wanted back into the room. Some students went to open the locked door but instead backed away.

"I'm guessing they saw something, but for some reason, they didn't open the door," Sayarath said.

The teen then turned the gun on people in a hallway, authorities said.

He has been charged in the deaths of students Mason Schermerhorn and Christian Angulo, both 14, and teachers Richard Aspinwall, 39, and Christina Irimie, 53, according to Georgia Bureau of Investigation Director Chris Hosey.

The teen was to be taken Thursday to a regional youth detention facility.

When the teen was not allowed back into his classroom, Sayarath said she heard a barrage of gunshots.

"It was about 10 or 15 of them at once, back to back," she said.

The math students fell to the floor and crawled around, looking for a safe corner to hide.

Two school resource officers encountered the shooter within minutes of a report that shots had been fired, Hosey said. The teen immediately surrendered and was taken into custody.

At least nine other people — eight students and one teacher at the school in Winder — were taken to hospitals. All were expected to survive, Barrow County Sheriff Jud Smith said. Authorities were still looking into how the teen obtained the gun and got it into the school with about 1,900 students in a rapidly developing area on the edge of metro Atlanta's ever-expanding sprawl.

"All the students that had to watch their teachers and their fellow classmates die, the ones that had to walk out of the school limping, that looked traumatized," Sayarath said.

Kassidy Reed joined a steady stream of classmates seeking counseling Thursday at the school system offices. The 17-year-old senior said she struggled to sleep Wednesday night in the aftermath of the shootings.

"The first thing you wake up and think about is like, somebody lost the coach, somebody lost their dad, somebody lost their best friend," Reed said.

Reed was taking a test Wednesday morning with a few others in a hallway when she heard gunshots just around a corner. A teacher across the hall opened a door so they could scramble inside a chemistry lab. Reed ducked under a table next to a classmate, whose cross necklace they both gripped as they prayed.

They were close enough to hear police order someone onto the ground, followed by what sounded a person being handcuffed. When officers escorted the lab students to safety, Reed said, she saw blood in the hallway and what looked like a disassembled firearm lying next to a body.

It was the 30th mass killing in the U.S. so far this year, according to a database maintained by The Associated Press and USA Today in partnership with Northeastern University. At least 127 people have died in those killings, which are defined as events in which four or more people die within a 24-hour period, not including the killer — the same definition used by the FBI.

The teen had been interviewed after the FBI received anonymous tips in May 2023 about online threats to commit an unspecified school shooting, the agency said in a statement.

The FBI narrowed the threats down and referred to the case to the sheriff's department in Jackson County, which is adjacent to Barrow County.

The sheriff's office interviewed the then-13-year-old and his father, who said there were hunting guns in the house but the teen did not have unsupervised access to them. The teen also denied making any online threats.

The sheriff's office alerted local schools for continued monitoring of the teen, but there was no probable cause for arrest or additional action, the FBI said.

Hosey said the state Division of Family and Children's Services also had previous contact with the teen and will investigate whether that has any connection with the shooting. Local news outlets reported that the teen's family home in Bethlehem, Georgia, was searched Wednesday.

On Wednesday evening, hundreds gathered at a park in downtown Winder for a candlelight vigil.

Christopher Vasquez, 15, said he attended to feel grounded and in a safe place. He was in band practice when the lockdown order was issued and hid with other students in a closet.

"Once we heard banging at the door and the SWAT (team) came to take us out, that's when I knew that it was serious," he said. "I just started shaking and crying."

He finally settled down once outside the school. "I just was praying that everyone I love was safe," he said.