Dozens of Tokyo firefighters were battling a blaze on Thursday at the world's largest fish market and one of the capital's most popular tourist sites, as grey smoke billowed over the city. There were no immediate reports of injuries or people trapped, media said. The 80-year-old Tsukiji fish market draws tens of thousands of visitors a year to its warren of stalls laden with exotic species of fish and fresh sushi, part of a tourism boom that is a key part of Prime Minister Shinzo Abe's economic plan. The fire broke out just before 5 p.m. and some 44 fire trucks were on the scene. But efforts to contain the flames were hampered by the area's narrow streets and tight-knit buildings. The cause was not immediately known.