Four people were killed and at least nine others injured when a shooter opened fire at Apalachee High School in Winder, Ga., authorities said. The deceased were two students and two teachers, police said. A 14-year-old suspect, whom the Georgia Bureau of Investigation identified as a student at the school, is in custody. He will face murder charges and be tried as an adult, authorities said.

Wednesday’s shooting was the deadliest at a U.S. school in more than a year and marks Georgia’s first fatal school shooting since at least 1999. Here’s what to know.

How did the shooting unfold?

Witnesses said they heard the first shots shortly after 10 a.m. Wednesday. A security alert advising a lockdown was posted on classroom video screens. Some students said they took cover in corners, while others crammed into a closet. Students recounted using rags to put pressure on a gunshot wound sustained by their teacher.

Within minutes of the first reports of an active shooter, school resource officers confronted the suspect, “who gave up and got on the ground,” Barrow County Sheriff Jud Smith said.

What do we know about the suspect?

State police identified the suspect as 14-year-old Colt Gray, a student at the school. He will be charged with murder and tried as an adult, officials said.

The FBI’s Atlanta field office said Jackson County sheriff’s officers interviewed Gray and his father in 2023, when Gray was 13, after receiving anonymous online tips about threats to commit a school shooting. The father told authorities that he had hunting guns in the house but that his son did not have unsupervised access to them, the FBI said. Officials said there was no probable cause for arrest or further action at the time.

If convicted, the 14-year-old suspect would be the youngest school shooter to kill multiple people on a K-12 campus since at least 1999, according to a Washington Post analysis of shootings perpetrated in the last 25 years. No child shooter younger than 15 has killed more than one person.

Who were the victims?

The Georgia Bureau of Investigation identified the four people killed as students Mason Schermerhorn and Christian Angulo, both 14, and teachers Richard Aspinwall, 39, and Christina Irimie, 53.

Nine people – eight students and one teacher – were taken to local hospitals with various injuries, GBI said. “All of our victims that are at the hospital are going to make it and going to recover well, as we’ve been told,” Smith said at a news conference Wednesday.

Several hundred people gathered Wednesday evening to mourn the victims at Jug Tavern Park in Winder’s city centre.

Sophie, a 15-year-old student whose mother did not want their full names used, recalled that her teacher was shot when she went into the hallway after hearing banging. There was “blood everywhere,” Sophie said. “[Another] teacher put pressure on his wound with rags. Then she went to get police, and a kid from my class and I put the pressure on the wound. My teacher was lying there saying, ‘Good job.’”

Then officers banged on the door. “Paramedics put my teacher on a gurney. We went to another classroom then out to the football stadium with our hands up,” Sophie added.

What gun was used?

Officials said the shooter used an “AR-platform-style weapon” but did not provide more details.

An AR-platform rifle, the AR-15, has been used in several of the most notorious and deadly mass shootings in American history.

Officials were still investigating how the Winder shooter obtained the weapon and brought it into school, the local sheriff said.

How have politicians responded?

Politicians paid tribute to the victims of the attack, with Democrats calling for gun-control legislation at the state and federal levels.

At a campaign stop in New Hampshire, Democratic presidential nominee Kamala Harris expressed condolences to the victims. “This is just a senseless tragedy on top of so many senseless tragedies,” she said. She then departed from her prepared remarks to lament that American children live with the fear of a shooter bursting through the doors of their school. “We’ve got to end this epidemic of gun violence once and for all,” Harris said. “It doesn’t have to be this way.”

In a statement on social media, Republican presidential nominee Donald Trump said: “Our hearts are with the victims and loved ones of those affected by the tragic event in Winder, GA.” He added: “These cherished children were taken from us far too soon by a sick and deranged monster.”

Georgia Gov. Brian Kemp (R) posted on X that he and his family were “heartbroken” by the tragedy. “This is a day every parent dreads, and Georgians everywhere will hug their children tighter this evening because of this painful event.” He urged all Georgians to join his family “in praying for the safety of those in our classrooms.”

“The entire Winder community is in my prayers, but we can’t pray only with our lips – we must pray by taking action,” Sen. Raphael G. Warnock (D-Ga.) wrote on X.

What do we still not know?

As well as the specific weapon used in the attack, the shooter’s motives remain unknown.

In a news conference Wednesday, Smith said investigators from the sheriff’s office and GBI had interviewed Gray. The investigators do not yet know why the shooting occurred, Smith said, adding that “We may not ever know.”

It’s also unclear how the weapon was obtained, who purchased it, and where and when they did so.

— Toluse Olorunnipa contributed to this report.