The top two floors of a three-story Brooklyn building collapsed into a busy shopping corridor Tuesday morning, the FDNY said. The front of the structure on Bedford Avenue between North Fifth and North Sixth streets in Williamsburg came down at about 12:45 p.m., according to the fire department. No injuries were immediately reported after the collapse and the building appeared to be vacant when it crumbled. It’s unclear if the strong winds battering the city from Tropical Storm Isaias played a role in downing the building. The buildings department did not immediately respond to a request for comment.