SAN DIEGO—Twelve San Diego Zoo visitors and two employees were brutally sedated Monday, when laid-off zoologist Dr. Brian Vermeer, 41, returned to his former place of work armed with a tranquilizer gun and began firing into a crowd. "It was kind of horrible," said Maria Christopher, 44, who witnessed the tranquilizing spree. "People were gently falling asleep over the course of 20 to 30 seconds everywhere." The spree ended when Vermeer turned his gun on himself, knocking himself out for half an hour.