Nuevo Leon state Gov. Jaime Rodriguez said the shooter died at a hospital and that the other three victims with head wounds were "fighting between life and death." The boy wounded in the arm was out of danger.
A video, apparently from the school's surveillance camera, shows a female teacher handing out materials and students seated at their desks when a boy opens fire with a pistol from a sitting position, hitting a boy sitting in front of him, who immediately slumps to the ground.
His first shot apparently misses his head, and then he runs out of bullets. The shooter runs to his backpack, apparently to reload, as his classmates cower at their desks.
He appears to say something to the surviving students, who begin to rush for the door, and then he shoots himself in the head and falls to the ground.
More From This Section
The crowded classroom was left with a jumble of overturned chairs, blood and fallen students.
"The classes were going perfectly well, the student stands up from his desk and pulls out a gun," Fasci said. He noted that photographs of the shooting had been posted to social media and said the person responsible would be punished. He also appealed to the news media to avoid using the images, which show minors.
The website of the American School of the Northeast says it offers bilingual education for students from preschool through ninth grade.
Fasci said the boy brought the gun from home. It was unclear how he got the .22 caliber pistol into the school. Mexico had once had a program to checked book bags at school entrances, but in many places it has fallen into disuse. "'There was a reason why book bags were checked. I think we are going to have to start doing it again," Fasci said.