LOS ANGELES (NewsNation Now) — A string of smash and grab robberies over the last week has luxury retailers and malls on high alert.

In a recent trend, thieves have smashed the windows of luxury retailers like Louis Vuitton, Nordstrom and Saks Fifth Avenue and grabbed merchandise before taking off on foot.

The slew of robberies and attempted burglaries stretch from California to Chicago.

In Los Angeles, a steel slinky-like barrier with barbed wire was established outside the Grove Mall to keep out intruders.

Police say hundreds of thousands of dollars worth of merchandise were stolen from a Chicago Neiman Marcus and Louis Vuitton store. In California, high-end stores in the San Francisco Bay area were hit for jewelry, sunglasses and suitcases among other items.

Corrie Barry, CEO of Best Buy, says in cases like this the safety of employees is her top priority.

“For our employees, these are traumatic experiences and they’re happening more and more across the country,” Barry said. “Obviously, their safety is our priority. We’re putting a multitude of measures in place whether that’s locking some of the products up, whether that’s working with our vendor partners or working with law enforcement.”

Security experts say stores have a responsibility to protect customers, and shoppers should never physically intervene.