RALEIGH (AP) -- Several colleges in North Carolina are reviewing their security policies.

University officials in North Carolina warned they may never be able to guarantee safety from violence such as what happened at Virginia Tech, where 32 people were killed Monday.

Administrators and security officers from around the state acknowledge that it's nearly impossible to lock down the state's higher education campuses, some of which cater to thousands of students every day. Even small colleges questioned the viability of securing school grounds.

North Carolina's higher education system includes dozens of universities, community colleges and private institutions that serve more than 300-thousand full-time students and many more part-time students.