It'd be neat to think that there is some sub-group of survivors utilizing an underground network of tunnels. I don't know though, with how long it took someone to respond, they could have parked a couple blocks away and went to the garden by foot. It could definitely go either way.

Well, either Victor will scare them away or someone is going to recognize Saul and stop before the trigger is pulled, it just doesn't smell like Mallers to me. I wonder if maybe these people were involved with picking over the surrounding area near the Tower that morning.