Sad personal memory:

We lived in Summit, NJ, about 15 miles due west of WTC. I went to the local hospital that afternoon to give blood. Halls were thronged with people who had the same idea. Medical staff told me they were too overwhelmed to take my donation that afternoon, but asked me to leave my phone # for the next day. Next morning I got a call saying they didn't need any more blood. I figured out why: too few survivors.

NY Transit was working that afternoon and evening. Our Rescue Squad set up ambulances and volunteers at our train station to help the wounded who got out of NYC. No one needed their services for the same reason.