A 15-year-old student opened fire with a gun at a private school in the northern Mexican city of Monterrey on Wednesday, seriously wounding himself, a teacher and three other students, state officials said.
Nuevo Leon state security spokesman Aldo Fasci said four of the injured, including the shooter himself, had bullet wounds to the head and were in extremely serious condition.
Fasci said a school video showed the male middle-school student first shot the 24-year-old teacher, then shot a 14-year-old girl and a 14-year-old boy in the head, and a 15-year-old classmate in the arm. He then pointed the gun at classmates before shooting himself in the head.
"This had never happened" in the state before, Fasci said.
He said the boy had been suffering from depression, but that the motive was under investigation.
The spokesman attributed it to "the situation that is happening everywhere. The children have access to the internet. This has happened in other countries."
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.
Mexico had been largely spared the phenomenon of school shootings that has hit the United States. In one of the few previous incidents, a 13-year-old student shot a 12-year-old classmate in the head at a Mexico City middle school in 2004, seriously wounding her.
At the height of Mexico's drug war between 2008 and 2011, schools in northern Mexico had considered a much greater threat the possibility that stray bullets from drug gang gun battles outside schools might enter classrooms. Some schools conducted "duck and cover" drills to combat that possibility.