ATLANTA >> Investigators in Georgia were piecing together how a teenager obtained the semiautomatic rifle he used to carry out a mass shooting at his school and whether there were any additional warning signs after authorities visited his home a year ago.

The student, identified as 14-year-old Colt Gray, opened fire on Wednesday at Apalachee High School in Winder, Georgia, killing two students and two teachers and wounding nine, law enforcement officials said.

The teenager and his father were interviewed in 2023 by local law enforcement in connection with online threats about carrying out a school shooting made on the gaming social-media platform Discord, according to investigators. Both Grays told investigators they had not made the threats. The father also told officials that he had hunting guns locked in a safe in the house and his son did not have access to them.

The shooter’s ability to obtain the semiautomatic rifle, any signs warning that he would actually carry out a shooting and his motive are focuses for investigators digging into the U.S.’ first campus mass shooting since the start of the school year.

Investigators from the Jackson County sheriff’s department interviewed the Grays in May 2023 after receiving a tip from the FBI about a threat posted in a Discord channel. Both Grays told investigators they had no connection to the Discord account on which the threats were made.

The sheriff’s investigators closed the case after being unable to substantiate that either Gray was connected to the Discord account, and did not find grounds to seek the needed court order to confiscate the family’s guns, according to police reports released by the sheriff’s office today.

“This case was worked, and at the time the boy was 13, and it wasn’t enough to substantiate,” Jackson County Sheriff Janis Mangum said in an interview. “If we get a judge’s order or we charge somebody, we take firearms for safekeeping.”

Gray was taken into custody shortly after the shooting. He will be charged and tried as an adult, the Georgia Bureau of Investigation said.

Gray was being held without bond at Gainesville Regional Youth Detention Center, Georgia Department of Juvenile Justice communications director Glenn Allen said today.

His arraignment is set for Friday morning before a Georgia Superior Court judge in Barrow County by video camera.

Officials identified those killed as two 14-year-old students, Mason Schermerhorn and Christian Angulo, and two teachers, Richard Aspinwall, 39, and Christina Irimie, 53. One teacher and eight students wounded in the attack remained hospitalized, MSNBC reported today.

The shooting revived both the national debate about gun control and the outpouring of grief that follows in a country where such attacks occur with some regularity.

People in Winder, a city of 18,000 some 50 miles (80 km) northeast of Atlanta, gathered on Wednesday night in a park for a prayer vigil for the victims.

Schermerhorn was an upbeat teenager who liked visiting Disney World, where his family was going on vacation soon, friends of his family told the New York Times. His mother told an Atlanta news channel that Schermerhorn had autism.

Friends of Angulo said he loved to make people laugh.

“He was a very good kid and very sweet and so caring,” wrote Lisette Angulo, who identified herself as the victim’s oldest sister on a GoFundMe page she created to cover his funeral costs. “He was so loved by many.”

Along with teaching math, Aspinwall was the football team’s defensive coordinator. He described himself as a “husband to a beautiful wife and dad to 2 amazing girls” on his X account, where he posted often about football and shared pictures of his family.

Irimie also taught math at the school. A friend told the Atlanta Journal-Constitution that she immigrated from Romania in the 1990s and was active in the expatriate community in Georgia, teaching traditional dances to children in her spare time.

The shooting was the first planned attack at a school this fall, said David Riedman, who runs the K-12 School Shooting Database. Apalachee students returned to school last month; many other students in the United States are returning this week.

The United States has seen hundreds of shootings inside schools and colleges in the past two decades, with the deadliest resulting in over 30 deaths at Virginia Tech in 2007. The carnage has intensified the pitched debate over gun laws and the right granted in the U.S. Constitution’s Second Amendment “to keep and bear Arms.”

Additional reporting by Brendan O’Brien, Liya Cui and Andrew Hay.