A student has opened fire at a private school in the northern Mexican city of Monterrey, seriously wounding himself, a teacher and another student, officials said.
Nuevo Leon state security spokesman Aldo Fasci said the male student shot the teacher, another student, and then pointed the gun at classmates before shooting himself.
Mr Fasci said the wounded had vital signs but were in an extremely serious condition.
He said the motive was still under investigation.
The website of the American School of the Northeast said it offers bilingual education for students from preschool through to ninth grade.
It was unclear how the student got the gun into the school.
Mexico once had a programme that checked bags at school entrances, but in many places it has fallen into disuse.