WINDER, Ga. — A 14-year-old student opened fire at a Georgia high school and killed four people on Wednesday, authorities said, sending students scrambling for shelter in their classrooms — and eventually to the football stadium — as officers swarmed the campus and parents raced to find out if their children were safe.

The dead were identified as two students and two teachers at Apalachee High School in Winder, about an hour’s drive from Atlanta. At least nine other people — eight students and one teacher — were taken to hospitals with injuries.