What is the appropriate action when an unauthorized person attempts to enter the facility?

Blocking the entrance when an unauthorized person attempts to enter the facility is the appropriate action because it helps to prevent potential security breaches and protects the safety of everyone within. This action serves to physically deter the individual from accessing restricted areas, which is crucial in maintaining the integrity of the facility's security protocols. By blocking the entrance, security personnel can also assess the situation more effectively and determine the appropriate next steps.

This response allows for further investigation into the individual’s intentions without escalating the situation unnecessarily. It aligns with general security practices that prioritize both prevention and response to unauthorized access.