There have to be numerous security cameras in the area which have given the police some idea of who they are looking for. It now appears that they have narrowed this down to devices planted in a garbage can. That has to be caught on video somewhere. And if it has been, the sooner the video is released the more likely it will tweak the memory of others who were in the area at the time.
In the case of the Unabomber, it was the fact that the boxes that held the explosive device were intricately carved...They might have caught him a lot sooner had that been made public.
Message to LE: Give the people all ya got!!