The suspect was speaking with investigators, but they declined to say if they knew what motivated him. They also did not say what type of gun was used in the shooting.
“What we see behind us is an evil thing today,” Sheriff Jud Smith said during a brief news conference on school grounds.
Smith said that his deputies quickly responded to the shooting after the sheriff’s department got word of an active shooter about 10.20am.
The gunman was confronted by a deputy in the school and the boy immediately surrendered, Smith said.
The school is about 80km northeast of Atlanta.
Local TV stations broadcast images of parents lining up in cars on a road outside the school, hoping to be reunited with their children. The school, which had an enrolment of nearly 1900 in 2023 began classes on August 1.
ABC News quoted a witness, student Sergio Caldera, as saying he was in chemistry class when he heard gunshots. Caldera, 17, told ABC his teacher opened the door and another teacher ran in to tell her to shut the door “because there’s an active shooter”.
As students and teachers huddled in the classroom, someone pounded on the door and shouted several times for it to be opened. When the knocking stopped, Caldera heard more gunshots and screams. He said his class later evacuated to the school’s football field.
The White House said in a statement that President Joe Biden had been briefed on the shooting “and his administration will continue co-ordinating with federal, state, and local officials as we receive more information.”
“Jill and I are mourning the deaths of those whose lives were cut short due to more senseless gun violence and thinking of all of the survivors whose lives are forever changed,” Biden said in a statement, calling on Republicans to work with Democrats to pass “common-sense gun safety legislation.”
Vice-President Kamala Harris, the Democratic Party nominee for President, called the shooting a “senseless tragedy”.
“We’ve got to stop it. We have to end this epidemic of gun violence,” Harris said at the start of a campaign event in New Hampshire.
Former President Donald Trump, the Republican nominee for President, wrote on social media that “Our hearts are with the victims and loved ones of those affected by the tragic event in Winder, GA. These cherished children were taken from us far too soon by a sick and deranged monster.”
The shooting was the first “planned attack” at a school this autumn, said David Riedman, who runs the K-12 School Shooting Database. Apalachee students returned to school in August; many other students in the US are returning this week.
The US has seen hundreds of shootings inside schools and colleges in the past two decades, with the deadliest resulting in more than 30 deaths at Virginia Tech in 2007. The carnage has intensified the pitched debate over gun laws and the US Constitution’s Second Amendment, which enshrines the right “to keep and bear arms”.