What we know after a 14-year-old boy was charged with killing 4 people at his Georgia high school.

A 14-year-old boy stands charged with four counts of murder, accused of using a semiautomatic assault-style rifle to kill two students and two teachers this week at his high school in Georgia. Colt Gray had his first hearing Friday after being charged as an adult in the latest mass shooting at a school in the U.S.

Immediately after that hearing, his father, 54-year-old Colin Gray, appeared in the same courtroom, charged with multiple offenses for allowing his son to have a weapon.

The shooting Wednesday morning at Apalachee High School in Winder, outside Atlanta, has left the father and son behind bars, families planning funerals and people wondering what happened and why.

How it happened

WHAT WE KNOW: Colt Gray was in algebra class when he left the classroom, according to classmates. One believed he was skipping class again. But Gray returned and knocked for someone to open the locked door. Students who went to the door saw something through the window and backed away. Classmate Lyela Sayarath said she saw Gray turn and then heard gunshots — ''10 or 15 of them at once, back-to-back.'' A school resource officer found the shooter, who surrendered at 10:26 a.m. Authorities say the suspect killed four people. Nine others were hurt, seven of them shot. The Georgia Bureau of Investigation says the suspect acted alone.

WHAT WE DON'T KNOW: Authorities have not identified a motive for the shootings. Officials also have not said where in the school the victims were shot. Eyewitness accounts indicate some were shot in a hallway and at least one in a classroom, however. It's also not known how the suspect got to school that day, whether he took a bus or got a ride; how the gun got into the school; and where it was ahead of the shooting. Authorities say the school does not have metal detectors.

Who the victims were

WHAT WE KNOW: Authorities have identified the four people killed as students Christian Angulo and Mason Schermerhorn, both 14, and math teachers Richard Aspinwall, 39, and Cristina Irimie, 53. The eight students and one teacher who were taken to the hospital are expected to make full recoveries. Angulo's sister Lisette described him on a GoFundMe fundraiser for his funeral as ''a very good kid and very sweet and so caring.'' A neighbor of Schermerhorn said he was an inquisitive boy who he watched grow up from around age 4.

Irimie was a recent immigrant from Romania who also helped teach a children's dance group. Aspinwall was also the defensive coordinator for the high school football team, an old-style football coach who loved his wife, daughters, students and football, according to the head coach.

WHAT WE DON'T KNOW: Just as we don't know a motive for the shootings, it's not known if the shooter targeted the victims or it was merely chance.

The suspected shooter

WHAT IS KNOWN: Colt Gray faces four counts of murder, but officials said Friday that more charges are coming. This isn't the teen's first interaction with authorities, who interviewed him over a social media post last year about possibly threatening to shoot up a middle school. Gray, then 13, said ''he would never say such a thing, even in a joking manner,'' according to a report filed by investigators. No action was taken because of inconsistent information about the social media account.

Colin Gray told the investigator back then that Colt had access to unloaded guns in the house but knew ''how to use them and not use them.'' He also said his son had struggled since he and his wife separated and Colt was picked on in school. The two shot guns together, and the elder Gray showed the investigator a cellphone photo of the boy from a recent trip with blood on his cheeks after shooting his first deer. It was ''the greatest day ever,'' the father said.

WHAT IS NOT KNOWN: Not much is known about the Grays between the investigator's visit in May 2023 and the shooting. They had lived in a neighboring county at the time of the interview but moved to Winder at some point. Investigative reports indicated when Colin Gray separated from his wife, two younger children moved with her but Colt lived with his dad. He was a recent transfer to Apalachee High School and missed a lot of classes, fellow students said.

Why the father was charged

WHAT WE KNOW: Colin Gray, who works construction, became the first parent of a school shooting suspect to be charged in Georgia, District Attorney Brad Smith said Friday. But in Michigan, two parents were previously convicted in a similar case. Gray has been charged with four counts of involuntary manslaughter, two counts of second-degree murder and eight counts of cruelty to children for knowingly allowing his son to possess a gun that authorities say was used in the shooting.

WHAT WE DON'T KNOW: Even though authorities allege Colin Gray allowed his son to have the assault-style rifle, it's not clear how or when the boy came into possession of it. The Georgia Bureau of Investigation is declining to release additional information because of the ongoing investigation. ''The shooter is alive and is facing charges and we are working on preparing a strong case that needs to go through the judicial process,'' the agency said on its website.