Final answer:
In an active shooter incident, immediately lying on the ground is False; it's better to follow the Run, Hide, Fight protocol for safety.
Step-by-step explanation:
The statement that you should immediately lie on the ground in an active shooter incident involving firearms is False. Lying down can make you an easier target and does not allow for quick mobility. Instead, it's recommended to follow the Run, Hide, Fight protocol. First, you should try to evacuate the area quickly and safely (Run). If evacuation is not possible, find a safe place to hide where the shooter is less likely to find you (Hide). As a last resort, and only if your life is in imminent danger, attempt to disrupt or incapacitate the shooter (Fight). The reference provided is focused on protection from blast and heat damage from explosives, not active shooter scenarios. Therefore, the advice to fall flat given in the reference is not applicable to an active shooter situation.