BRUSSELS (Reuters) - The sweet smell of waffles is familiar in Belgium but on Thursday people were left choking as a fire at a waffle factory sent a dense black cloud across Brussels, disrupting some rail traffic in the capital. Police said the blaze at the Milcamps factory, which produces the national sweet treat in various regional variants, broke out at lunchtime. It was not immediately clear what started it or whether anyone was hurt.  A lot of smoke has been emitted and we are advising people to keep doors and windows shut and to stay inside. Drivers should close air vents in their cars,  local police said. A sharp smell of burned waffle caused coughing in the city center, 6 km (4 miles), from the blaze. Belgian waffles, traditionally sold from mobile vendors and street kiosks, have become popular around the world. They are batter cooked between hotplates patterned according to various regional traditions and dusted with icing sugar.  Their history dates back to the wafers baked for Mass in the medieval monasteries of the Low Countries.    
Who burned the cakes? Belgian waffle fire chokes Brussels