The Christmas shopping season is being marred by a new crime wave hitting America’s cities as “smash and grab” attacks escalated at stores across the country on Black Friday and over the weekend. In all of the incidents, authorities described “flash mobs” of thieves who rushed in, overwhelmed workers, looted stores, and made off with tens of thousands of dollars in goods. California police reported a rash of such robberies, including tens of thousands of dollars in merchandise stolen from a Nordstrom. About 20 people were involved in the smash-and-grab theft, stealing about $5,000 worth of merchandise and leaving roughly $15,000 worth of damage to the store when they fled. During the incident, the mob reportedly used a chemical agent against a security guard, who was treated at the scene. Similar brazen thefts recently occurred in the San Francisco Bay Area and Beverly Hills in which groups of people, some carrying crowbars and hammers, ransacked high-end stores and stole jewelry, sunglasses, suitcases, clothing, and other merchandise before fleeing in waiting cars.