CONCORD (KPIX) — A brazen crew of smash-and-grab robbers took over a Concord jewelry store Monday night, ransacking display cases before fleeing with an undisclosed amount of merchandise.

Concord police said the incident took place at 7 p.m. while shoppers were inside the Sun Valley Mall.

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According to investigators, nine masked suspects, armed with hammers, ran into Iceberg Diamonds and began smashing and emptying all the display cases. Police said store employees tried to intervene but were kept back by the hammer-wielding thieves.

As quickly as the robbers arrived, they were gone, leaving the store’s staff to clean up the broken glass and inventory the loss.

Police said some mall shoppers called reporting what they thought were gunshots heard, but the noises were the sounds of the hammers breaking glass. No shots were fired.

In downtown Pleasant Hill store employees told KPIX, it’s common for people to grab items off the shelves and walk away.

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“I’m not supposed to be stopping people from smashing windows or stealing things. I’m not getting paid for that, I’m not getting paid for risking my life for that kind of thing,” says Mack Denham.

Employees say they have been told to just call security or police when thefts occur.

Businesses are trying to take steps to protect themselves and their employees. Most have surveillance cameras and a system to limit the cash left in registers. Employees, though, are worried robbers are becoming more brazen.

Employee Rebecca Sanders says, “It is a little overwhelming for safety reasons because people are stealing things and it can be concerning.”

Meanwhile, the Iceberg Diamond store robbery was under investigation. Concord police urged anyone with any information on the case to contact Detective Christine Corey at 925-603-5828.

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Andrea Nakano contributed to this report.