Parents at one Bronx high school are insisting that a lack of security is to blame for recent and repeated acts of violence on school premises.Parents say a fire drill at Dewitt Clinton High School turned violent when a group of students attacked several others. One parent says a student was beaten underneath a car. Now, parents are insisting something be done about what they say is a routine occurrence at the school. School officials maintain Dewitt Clinton is a safe place for its students. Parents say if that were so, their children wouldn?t fear going to what should be a safe haven.Other parents say with the size of the school, they can understand the difficulties of managing a large student body. The Department of Education says only two students were taken to the principal?s office as a result of the fight.