The post-Thanksgiving door buster sales event phenomenon known as "Black Friday" has come to mark the annual beginning of the Christmas shopping season in the U.S. Unfortunately, for many retailers, it has also become synonymous with out of control behavior by consumers as much as it has with deep discounts on merchandise.

This year was no exception with numerous incidents reported at stores across the country. One of the most widely publicized events occurred in the Los Angeles area when a woman attacked fellow shoppers with pepper spray in an attempt to grab a discounted video game console. However, the majority of serious incidents occurred in the parking lots of retailers.

A man in San Leandro, Calif., was shot by robbers when he refused to relinquish items he had just purchased. In Connecticut, a woman waiting for her husband at a home improvement store was carjacked at gunpoint.

According to retail security experts, these incidents demonstrate the importance of having comprehensive security plans in place to help mitigate the risks to shoppers in parking lots.

"Customers are easy targets in parking lots," said Pat Murphy, president of Houston, Texas-based LPT Security Consulting. "They are focused on getting into or out of the store and during the holidays, there are generally a lot of cars moving around so it is difficult to sense a slow moving vehicle that may be a threat."

Murphy, a former area loss prevention manager with Sears and the former director of loss prevention operations at Eckerd drug stores, said that having a visible security presence can act as a deterrent on parking lot crime.

"It is going to prevent some level of crime in your parking lot," he said. "In short, the visibility to me serves as a deterrent and it helps the customers feel better as well."

Once a retailer decides that they need a visible security presence, Murphy said the challenge becomes figuring out how much security is adequate.

"There is no staffing ratio that says for 'X' number of acres or 'X' number of parking spaces you should have 'Y' number of security officers patrolling, so it really is an educated guess at best," Murphy explained. "They have to base their decision on what type of incident history they've had in the past."

Retail security consultant Curtis Baillie, principle at Security Consulting Strategies, LLC, said that retailers inviting the public in for these special sales need to extend the same protections they would employ for shoppers inside the store to their parking lots.