There are times when remaining inside the building is the safest alternative. In a preventive lockdown, perimeter doors are locked to keep a situation from escalating. Preventive lockdown is a realistic option for the numerous situations that can quickly escalate into an emergency unless security is immediately increased.
A preventive lockdown allows for limited normal activities to take place, such as continued teaching within locked rooms. Movement in hallways and other areas is stopped while the situation is investigated and addressed. 
