Regardless of the industry, every single security guard must complete a shift report at the end of every shift! The shift report should include information regarding their safety checks/rounds, whether or not anything unusual was seen or heard, and if any kind of incident unfolded on the property. When documenting incidents, any possible information that can be documented, needs to be! (Who was involved, what happened, time of day, location, resolution, etc).
Not only is this information helpful for managers (to help solve problems) and potential lawsuits/claims, it is also required by the state! And, the state will randomly choose companies to audit! When a company has poor or nonexistent records, they can get in serious trouble.