Investigators continue to look for answers about what happened at Apalachee High School in Barrow County, Georgia, with county Sheriff Jud Smith telling reporters Wednesday that it would take “multiple days” to get a full understanding of the school shooting. Here is what we know about the school shooting at Apalachee High School.

Who were the victims?

The Georgia Bureau of Investigation announced Thursday that four people were killed in the shooting, including two students and two teachers. The students killed were Mason Schermerhorn, 14, and Christian Angulo, 14, while the two teachers killed were Richard Aspinwall, 39, and Christina Irimie, 53.

The agency also said nine other people, eight students and one teacher, were hospitalized with injuries, but did not release the names of those injured.

Who was the alleged shooter?

Police announced the shooter was Colt Gray, 14, a student at the high school. He is in police custody and has been charged with murder. Law enforcement also said Gray will be tried as an adult.

The FBI’s Atlanta division said Wednesday it “received several anonymous tips about online threats to commit a school shooting at an unidentified location and time” in May 2023, and referred the information to the Jackson County Sheriff’s Office, who questioned Gray and his father.

“The Jackson County Sheriff’s Office located a possible subject, a 13-year-old male, and interviewed him and his father. The father stated he had hunting guns in the house, but the subject did not have unsupervised access to them. The subject denied making the threats online. Jackson County alerted local schools for continued monitoring of the subject,” the statement from FBI Atlanta said.

“At that time, there was no probable cause for arrest or to take any additional law enforcement action on the local, state, or federal levels,” the statement continued.

What was the law enforcement response?

Authorities in Barrow County received initial reports about an active shooter at the school at 10:20 a.m. EDT Wednesday, with a resource officer at the school also indicating there was a shooter. Multiple law enforcement agencies were dispatched to the high school at roughly 10:23 a.m., and were on scene within minutes.

Smith told reporters the school resource officer engaged the shooter shortly after the shooting began, with the shooter surrendering and the officer taking him into custody shortly after.

Law enforcement has said there is no evidence of multiple shooters or that there was a list of schools being targeted.

What are the reactions to the shooting?

Gov. Brian Kemp (R-GA) said he and his family were “heartbroken” by the shooting and he will make all resources available to the affected community as they recover from the tragedy.

“This is a day every parent dreads, and Georgians everywhere will hug their children tighter this evening because of this painful event,” Kemp said in a statement Wednesday. “We continue to work closely with local, state, and federal partners to make any and all resources available to help this community on this incredibly difficult day and in the days to come.”

President Joe Biden also said he and the first lady were mourning the deaths of those killed in the shooting and called for further gun control measures.

Vice President Kamala Harris offered condolences and vowed that “we must end the epidemic of gun violence in our country once and for all,” in a statement on Wednesday.

“This is a senseless tragedy — and it does not have to be this way,” Harris said.

During a town hall on Fox News hours after the shooting, former President Donald Trump vowed to “heal our world” if he is elected back to the White House in November.