John Martin, 41, chief custodian and operator of the video surveillance system at Gloucester Catholic Junior/Senior High School in Gloucester City, N.J., admitted he installed small cameras, hidden in ventilation ducts and smoke detectors, in eight rooms that included rooms in which students changed clothes, the Camden County, N.J. Prosecutor's Office said.
Martin was arrested Wednesday and charged with third-degree invasion of privacy.
Some of the photographs were of nude students and were discovered on his school-issued cellphone, WCAU-TV, Philadelphia, reported.
Parents reacted with anger, the Philadelphia Inquirer said Thursday, quoting an unnamed mother of a student saying, "It's outrageous. I can't believe it. I'm really in shock," when she learned her daughter was among the students photographed.
Most of the photographs were of female students in various states of undress, authorities said.
Notable deaths of 2014 [PHOTOS]
Cyclist struck and dragged underneath car