MEXICO CITY (AP) - Authorities in Mexico's Gulf coast state of Campeche said Wednesday they are investigating how a porn video was made by sixth-graders inside their school.

State Education Department spokesman Omar Kantun said the video was apparently made in an empty classroom during recess in late April.

"It is real, the case is real, the video exists," Kantun said. "The Education Department is very concerned."

He said an investigation is being conducted by his department and the teachers union to determine whether any adults were involved.

Kantun said the teacher who uses the classroom did not appear to have been present when the video was made. He said no disciplinary action has been taken against any students or teachers as of yet. He said the students involved are being given psychological counseling.

The incident occurred in late April at a grade school in the town of Calkini, which is in a relatively conservative and heavily Indian area. Three boys are seen on the video engaging in oral and anal sex recorded on a cellphone by a fourth person, apparently another student.

The mother of one of the boys saw the video on the Internet and notified authorities, Kantun said. He said the video had since been taken down.

Authorities didn't announce the students' ages, but sixth-graders in Mexico are generally 12 or younger.