Final answer:
Law enforcement and security personnel have the authority to secure gates without notice in response to security breaches or threats.
Step-by-step explanation:
Authorized personnel to secure gates without notice typically includes law enforcement, border patrol agents, or security personnel in charge of safeguarding a particular area. Situations where there might be an immediate need to secure gates with no notice could involve a breach of security, such as an unauthorized entry or potential threats to the area being protected. The urgency depicted in the narrative where agents need to respond quickly to a hole cut in a pedestrian fence implies their authorization to act without prior notice to maintain security and address potential illegal activities.