KELLER (CBSDFW.COM) – Hundreds of students in the Keller Independent School District are preparing for upcoming graduation exercises, but more than a dozen are not being allowed to participate in activities.

The students have been banned from Saturday’s graduation exercise after participating in a number of senior pranks.

“We are holding responsible those students who stepped across that line from harmless prank to potential danger,” explained Keller ISD Board Trustee Melody Kohout. “The incidents that happened at the school, this past week, were not the normal senior prank-level incidents. That is what has led to the level of punishment that has been given out.”

School district officials say they have a level of tolerance for end-of-year pranks, but things can go too far.

“Normally it is a toilet paper fight, or water balloons, water out in the parking lot – something like that. And we expect that,” Kohout said.

The pranks included everything from a huge food fight, to the release of crickets and snakes in school hallways, to the tossing of balloons filled with baby oil.

School officials say the line has to be drawn when pranks get dangerous.

“What changed it was the safety factor – when baby oil was added to the water balloons, which made it dangerous for the other students who were trying to leave the area,” Kohout said. “We do not want to see this escalate next year to where a student does receive bodily harm or worse.”

As many as 13 students have been banned from Saturday’s commencement.

Another group of students are also being punished for their role in the pranks.

In a statement Keller ISD administrators said the second set of students had “a less active role” in the pranks and will be allowed to participate in graduation ceremonies, but the teens must be accompanied to the event by their parents, will be sequestered from their classmates before graduation and will be “monitored’ during the ceremony.

All of the students involved in the pranks were students at three schools — Timber Creek High School, Central High School and Keller High School.

Keller ISD officials say the investigation into the pranks and their participants continues. Some YouTube videos have been uploaded, although they do contain some vulgar language.