Sheriff’s deputies interviewed the boy and his father, who “stated he had hunting guns in the house, but the subject did not have unsupervised access to them”, the FBI said.
The suspect, who was 13 years old at the time, denied making the online threats and officials “alerted local schools for continued monitoring of the subject”.
“At the time, there was no probable cause for an arrest or to take any additional law enforcement action on the local, state or federal levels,” added the FBI statement.
Sheriff Jud Smith described the attack as “pure evil” and said officers were on scene within minutes of receiving 911 calls at 10:20 local time (14:20 GMT).
Two officers assigned to the school “immediately encountered the subject”, the sheriff said, adding that the boy “immediately surrendered”.
The boy has been interviewed and spoke with investigators once while in custody, Sheriff Smith said.
The sheriff added that no motive had been identified and that law enforcement did not know of “any targets at this point”.
Students described chaotic scenes as alerts went out that an attacker was on campus. Classes at Apalachee began last month, but many students across the US are returning to schools this week.
Lyela Sayarath, who was in the alleged attacker’s class, told CNN that the suspect left the room at the beginning of an algebra lesson.
She said he came back and knocked on the door, which had locked automatically, but another student refused to let him in after noticing he had a gun.
Lyela told CNN the attacker then went to the classroom next door, where he began shooting.
(Except for the headline, this story has not been edited by PostX News and is published from a syndicated feed.)
