The 14-year-old student who killed four of his classmates in the US state of Georgia was questioned by police last year about online threats, the Federal Bureau of Investigation (FBI) said.

In May 2023, Colt Gray was questioned by police who believed he was behind internet posts that contained images of guns and warned of a school shooting.

The FBI said its National Threat Operations Center alerted local law enforcement after receiving reports of “online threats to commit a school shooting at an unknown location and time.”

After determining the location of the threats, police questioned the teenager and his father.

While the teenager denied making the threats, his father told police that he had hunting weapons in the house, but that the then 13-year-old “did not have unsupervised access to them.”

“At that time, there was no reasonable cause for an arrest or for further law enforcement action at the local, state or federal level,” the FBI said in a statement.

On Wednesday, the boy opened fire with an assault rifle at Apalachee High School, killing two teachers and two students, investigators said.

Eight other students and a teacher were injured in the attack. Gray was arrested on school grounds and will be tried as an adult.

The school sent a message to parents saying it was “currently in a hard lockdown following reports of gunshots.”

Survivors described the moment Gray began attacking students. One student told the BBC she saw him leave a class after a maths lesson and when he returned, he had a gun in his hand. One of her classmates saw the gun and refused to open the door for Gray, even though he continued to bang on it.

Gray then went into the next classroom and opened fire.

According to the BBC, this was the 23rd school shooting at a US school in 2024. So far this year, 11 people have been killed and 38 injured in such attacks.