(Vancouver, WA) -- Classes will resume today at a Vancouver middle school that was evacuated because of a safety scare. Officials say trusses supporting a heating and air-conditioning unit on the roof of Pleasant Valley Middle School are being shored up after they were found yesterday to be failing. Crews began investigating after a staff member reported the ceiling in the school library appeared ready to cave in. The ceiling is undergoing repair, and other HVAC units on the school buildings were inspected with no problems found.