Well If I was mr. suicide bomber in the back of that truck.. I would simply detonate the moment someone tried to evacuate.. .. nope not getting away from me.
If you mean evacuating before the truck even gets there... well If there I really wanted to just kill some people for terror.. if the place looked like it wasn't largely populated.. I would just drive to a more populated place.. and *BOOM*.
Evacuation can be nice.. but it can sometimes only change the target... making it harder to prevent.
And don't we have scanners now-a-days that could give us a REALLY good idea whether or not the bomb was in the truck(depending on time constraints such actions could or could not be applicatable).
