A diamond jewelry store in the East Bay has been cleaned out after video shows thieves breaking into the shop, smashing glass cases with hammers and stealing nearly everything. Witnesses and employees at Iceberg Diamonds in Sun Valley Mall in Concord said they were scared when the smash-and-grab occurred Monday about 7:30 p.m., 90 minutes before closing. Concord police released six seconds of surveillance video inside the store, showing men in hoodies smashing the glass case. All the men wore black sweatshirts, except one, who wore white. The hoods were over their faces, making it nearly impossible to get a description. Police said a total of nine people stole the jewels. Employees tried to intervene and were kept back by the “hammer wielding criminals,” police said in a statement. Concord police responded to the scene but by the time officers arrived, the suspects had taken off. The thieves ran out of the store and through a Red Robin restaurant inside the mall, which did not respond for comment.