What is the first thing to do in response to a telephoned bomb threat?

In the event of a telephoned bomb threat, the first action should be to engage the caller by asking detailed questions. This is crucial because gathering as much information as possible can provide critical insight into the threat's validity, the caller’s identity, and any specific details about the bomb, such as its location or detonation timing. Knowledge from the caller can aid law enforcement and security personnel in assessing the situation swiftly and effectively.

Engaging with the caller also allows for a calm and controlled response. While the other options might seem relevant in the context of handling a bomb threat, their placement as the first action does not support a thorough and informed security protocol. For example, hasty actions like hanging up or clearing the area might lead to unnecessary panic and disrupt the process of gathering vital information that could prevent injury or loss. Therefore, asking detailed questions is paramount in the initial response to a bomb threat.