SAN DIEGO (KGTV) -- San Diego Unified School District officials confirmed to 10News Thursday that a teacher has been placed on leave while investigators look into accusations that he exposed a sixth-grade class to pornography.

Officials said they were first notified Monday after a parent reported the alleged incident happened during a physical education class at Horace Mann Middle School, located at 4345 54th Street in San Diego.

"San Diego Unified is investigating the incident that allegedly occurred at Mann Middle School. The employee has been placed on leave pending the investigation,” district officials said.

The district said it has spoken with at least 10 students regarding the report. There were at least 24 students in the class.

District officials and district police are investigating.

"It's reprehensible," Craig Tinson, whose 12-year-old grandson attends the school, said. "Becuase the students are very impressionable. They're looking for adults to be the leader and unfortunately, it was compromised on this occasion."

A parent of one of the students told 10News that her son was in the class when the teacher allegedly showed the students an adult video of a man and woman engaged in sexual activities. The parent said the video was on for about 20 seconds before it was turned off.

This is a developing news story. Stay with 10News for updates.