The school district shall maintain a warning system designed to inform students, employees, and visitors in the facilities of an emergency. The system shall be maintained on a regular basis under the maintenance plan for the school district buildings and sites. Students shall be informed of this system. Each classroom and office shall have a plan for helping those in need of assistance to safety during an emergency. This shall include, but not be limited to students and employees with disabilities. Licensed employees shall be responsible for instructing students on the proper techniques to be followed during an emergency.