Transformers 3 director Michael Bay talked with the Chicago Sun-Times about some of the scenes they are currently filming on the city streets of Chicago until the end of August. Possible spoiler ahead:

Though Bay keeps his Transformers 3 story line close to the vest, he did reveal the Chicago footage ''is at the very end of the movie and the city is under alien attack, so it's very critical and important to the film's climax.'' RELATED: Back to the Future Meets Transformers in Comic Book Crossover Coming This October

The scene shot Monday between Michigan and Wabash focused on ''a number of base jumpers who are part of Josh Duhamel's unit. The heroes in this movie have very few people coming to help them this time. I like to think of it as the 'Black Hawk Down' version of 'Transformers' -- it's much more intimate in terms of what's happening.

''Something very bad has happened to America -- and this is at the very end of the movie.''