Fire on the "Batman" Set

A fire broke out on the roof of a vacant former post office building in Chicago on Tuesday, where a movie crew had been filming scenes for the upcoming Batman sequel "The Dark Knight," starring Christian Bale. At least a dozen ambulances and fire trucks were on the scene (where's a superhero when you need one?!) just south of Chicago's downtown business loop.

The crews had been filming there all week and letters affixed to the side of the old post office read: "Gotham National Bank." When the fire first broke out, a witness said "We assumed it was part of the movie." Some special efx.

A producer for the film tells TMZ that no actors were in the area at the time. He says that the fire started in an airway duct that is used for a railway underneath the building, the sprinkler system was activated, and the building was evacuated.