Updated

Three Brooklyn high school seniors will be banned from their graduation ceremony because of a prank involving a cake that apparently was laced with laxatives.

Department of Education spokeswoman Margie Feinberg said Wednesday that the cake sickened two crossing guards, a social worker and three teachers — two of them sought treatment at a hospital.

As punishment, the students will finish their year at an alternative learning center. A parent or guardian will have to escort them if they need to stop by the Brooklyn School for Global Studies.

Feinberg says the students didn't realize anyone would be harmed. The NYPD is testing the cake's ingredients, but Feinberg says a laxative is suspected.