Fire Engineering has done several features on this in the past year, you should check them out.
You may also want to check out "Building Construction for the Fire Service" by (first name?) Brannigan. I think it is in volume 4 now. This book was published long before 9-11 and is kinda like and "I told you so" if you know what I mean.
I would strongly recommend researching the fire service as opposed to any planning related agencies, they are alot better informed when it comes to terrorism, terrorism response, etc and your just not going to get that kind of info from a landscape architect, planner, etc.
You could also back into your topic. There are plenty of resources on how to build a bomb, create terror, etc. Find a way for your design to defend against it.