In first thread someone said there was a lift (elevator) that came down between Lindt and outside, like an entryway...as they were warning those upstairs evacuating not to use as they could be taken hostage...maybe that is where the policeman was standing out of sight. The café has several entrances it seems.
matt1234 posted, just above your post, that police are on the 2nd floor of the building the café is in. That lift may be how they got up there.