Los Angeles — Horrific video from Oct. 5 shows another 7-Eleven being violently looted by a “flash mob.” The lone staffer at this location tried desperately to shut the doors before he was threatened with a concrete slab by one of the masked rioters. Once inside, the mob attacked the clerk and looted the store. Over a dozen 7-Eleven stores have been targeted by “flash mob” robberies across Los Angeles in recent months.