Before “lockdown” flashed on classroom screens last Wednesday and Apalachee High School changed irrevocably, its 1,900 students were getting into the groove of a new academic year.

Seniors with cars had started decorating their assigned parking spaces, a perk available only to their class, painting them with flowers and Bible verses and a rendering of SpongeBob SquarePants.

The varsity Wildcat football team had played its first three games — losses, but there was still the rest of the season. Bar-B-Cats, a student club with a mission to raise “the next generation of pitmasters,” had catered its first few events of the school year.

But on Sept. 4 — five weeks into the new academic year — a 14-year-old freshman at the school in Winder, Ga., opened fire with an AR-15 during second period, officials said, killing two students and two teachers in the deadliest school shooting in Georgia’s history. Classes and events were canceled indefinitely.

The initial horror and shock of the attack has by now given way to the probing anguish that so often follows a school shooting. Students, parents and teachers are wondering what the rest of the school year will feel like and what challenges it will entail — just as they wonder how a student’s unraveling could have turned so violent.

“I’m still trying to question that,” said Myo Naing, a junior who credited one of his friends for running across their classroom to slam the door when the shooting started.