Witnesses said they saw a glare of light and heard a tremendous boom as lightning struck the water off of Venice Beach around 2:30 p.m. Sunday. Swimmers cooling off on a muggy day, volleyball players on the sand and people strolling the famous boardwalk were jolted. Twelve other people, including a 15-year-old boy, were examined after they felt the effects of the lightning, ranging from anxiety to a man who needed cardiopulmonary resuscitation. Earlier, off the coast, lightning struck a 57-year-old man on a golf course on Santa Catalina Island but he was taken to a hospital in stable condition, said Steve Denning, a law enforcement technician with the Los Angeles County Sheriff's Department. The lightning strikes occurred as a fierce but brief thunderstorm hit the island, dumping more than three-quarters of an inch of rain in about two hours, causing minor flooding and setting two small fires in the brushy backcountry that were quickly doused.