An emergency may prevent the safe evacuation of a school building and require steps to isolate students and faculty from danger by instituting a school lockdown. In an interior lockdown situation, all students are kept in classrooms or other designated locations that are away from the danger. Faculty members are responsible for accounting of students and ensuring that no one leaves the safe area. School personnel will also secure building entrances, ensuring that no unauthorized individuals leave or enter the building. Exterior lockdown procedures may also be used to ensure the safety of students when an incident occurs in the community. Parents are permitted access to the building and to their children if it is safe for them to do so.