A person who is paid to protect property, assets or people is known as a security guard or security officer. Security guards, in New York, are usually privately and formally employed personnel who protect property and deter illegal and inappropriate actions, by observing for signs of crime and then taking action or by reporting to their client and emergency services as appropriate.
A patrol is a group of personnel, such as police officers or soldiers that are assigned to monitor a specific geographic area. In places like New York small groups or individual units are deployed from a larger formation, to achieve a specific objective and then return. The tactic of patrolling may be applied to ground troops, armored units, naval units, etc.