The shooting is the latest in a string of violent incidents on the resort-studded coast, and came in the same week that a special battalion of National Guard troops were assigned to protect the area. Mexican marines with bulletproof vests, helmets and assault rifles were seen patrolling Cancun’s tourist-crowded beaches following the Tuesday shooting. On Nov. 5, a commando of drug gang gunmen stormed a beach at Puerto Morelos, a resort just south of Cancun, and opened fire in front of luxury hotels, executing two drug dealers from a rival gang. The dramatic shooting attack sent tourists scrambling for cover....