A 15-year-old boy was detained in Georgia after other students on a school bus reported overhearing him reference the deadly Apalachee High School shooting and make threats about "finishing the job," authorities said.

Sheriff's deputies in Jackson County, which neighbors Barrow County where the shooting took place Wednesday, were notified that same day about the alleged threat, Sheriff Janis Mangum said in a press release. The boy, who was later charged, was being held at a juvenile detention center in Gainesville, Mangum said.

The threat came on the same day that four people were killed and nine were injured when a 14-year-old student in rural Georgia opened fire at a high school. The four victims killed were identified as two students and two teachers at Apalachee High School in Winder, an Atlanta suburb of 18,300 people.

The suspect in the fatal shooting, identified as Colt Gray, was arrested and charged with murder and is expected to be prosecuted as an adult, officials said.

Teen threatened to commit shooting at Jackson County school

The 15-year-old boy in Jackson County was reportedly overheard making statements about the shooting, indicating that he was "planning on finishing the job" by committing a shooting at another school, Mangum said in a statement.

The news release did not specify in which school district or city in Jackson County the threats were made. It was also not clear what charges the boy faced.

The teen was interviewed at the sheriff's office and had been in custody as of Thursday afternoon, according to Mangum.

USA TODAY left a message Friday morning for Mangum that was not immediately returned.

Apalachee High School shooting victims

Reports about an active shooter at Apalachee High School started coming in around 10:20 a.m., prompting law enforcement officers to respond and place the school on lockdown.

Once officers encountered the shooter, he immediately surrendered and was taken into custody, Georgia Bureau of Investigation Director Chris Hosey said at a news conference Wednesday afternoon.

The four victims killed in the rampage included two students and two teachers. They were previously identified as Mason Schermerhorn, 14, Christian Angulo, 14, Richard Aspinwall, 39, and Christina Irimie, 53.

Nine other people – eight students and one teacher – were taken to hospitals with injuries and were expected to survive.

Father of teen suspect also arrested after fatal school shooting

The suspected shooter Colt Gray, a 14-year-old student, was arrested and charged with murder, according to the GBI.

"Additional charges are expected," the GBI said earlier Thursday.

Hosey told reporters that the weapon Gray is suspected of using was an AR-platform style rifle. A motive remains unclear.

Gray was interviewed by local law enforcement last year, FBI Atlanta revealed in a post on X Wednesday evening.

FBI's National Threat Operations Center received several anonymous tips about online threats to commit a school shooting in May 2023, according to the Atlanta office. The threats, which didn’t specify a place or time, had pictures of guns and were traced back to Georgia.

The FBI Atlanta office said it shared the information with the Jackson County Sheriff’s Office, who then interviewed Gray and his father.

Gray's father was then charged Thursday in connection with the attack – making him the latest parent who authorities seek to hold accountable for their children’s violent actions.

Colin Gray, 54, was charged with four counts of involuntary manslaughter, two counts of second-degree murder, and eight counts of cruelty to children, according to the Georgia Bureau of Investigation. Online jail records show that the elder Gray was booked into the Barrow County Detention Center on Thursday night and being held without bond.

Contributing: Thao Nguyen, Jeanine Santucci, Ryne Dennis, Fernando Cervantes Jr. and Cybele Mayes-Osterman, USA TODAY

Eric Lagatta covers breaking and trending news for USA TODAY. Reach him at [email protected]