SAN RAFAEL -- Some students at three San Rafael schools are unhappy with the presence of surveillance cameras.

The campuses of San Rafael and Madrone high schools and Glenwood Elementary School are dotted with 23 video cameras installed on ceilings and atop outdoor tripods -- virtually everywhere but in restrooms and classrooms.

The high-tech cameras are operated 24 hours a day.

"It's kind of like an invasion of privacy," said Sara Melton, 16, an 11th-grader at San Rafael High. "It is kind of weird knowing that the cameras and our administrators are able to see every little thing you're doing as you walk down the hall."

San Rafael's surveillance cameras -- by far the most advanced network in Marin County's public schools -- are part of a growing trend across the nation.

Some school officials here say the cameras are intended to thwart petty crime. Others cite them as a deterrent to violent acts such as school shootings.

"The purpose of the video cameras is primarily to protect against vandalism from outsiders, and not to monitor the daily interactions of students," said Rebecca Rosales, assistant superintendent of curriculum and programs for the San Rafael City Schools District./AP