A Georgia grand jury indicted a teenage boy and his father on dozens of charges, including murder, in connection with a mass shooting last month that killed four people at Apalachee High School, officials said Thursday.

A Barrow County grand jury indicted Colt Gray, 14, on 55 counts, including four counts of malice murder and four counts of felony murder, in the Sept. 4 shooting on the campus in Winder, according to court records.

He is being charged as an adult with fatally shooting two students and two teachers and wounding nine other people.

He was also indicted on charges including first-degree cruelty to children and aggravated assault.

His father, Colin Gray, was indicted on 29 counts, including second-degree murder, second-degree cruelty to children, involuntary manslaughter and reckless conduct, according to records from the Barrow County District Attorney's Office.

The father and his son were indicted separately.

Two law enforcement sources familiar with the investigation told NBC News last month that Gray gave his son an AR-15-style rifle as a gift.

Gray gave him the weapon at some point after law enforcement officials interviewed them in May 2023 in connection with reports of online threats to carry out a school shooting, the sources said.

Both are scheduled to appear for arraignment on Nov. 21, when each would formally enter a plea. Colin Gray is being held in the Barrow County jail, and his son is being held in a juvenile detention center in Gainesville, The Associated Press reported.

Barrow County District Attorney Brad Smith said last month that Colin Gray's charges marked the first time in state history a parent of a suspected school shooter was charged.

Killed were Mason Schermerhorn, 14; Christian Angulo, 14; Richard Aspinwall, 39; and Cristina Irimie, 53.