This is a situation that points at the ridiculous and debilitating position such tight gun laws place citizens in.
The perp has the weapons, the average citizen is discouraged from having one.
This county now has the ATF, FBI, homeland security, and surrounding counties volunteering police aid, etc. There was a time that even w/o these resources the community would team up and network to respond quickly to the next incident.
How inpracticable would it be for an armed citizens/authorites combo to be prepared to block roads within a reasonable circumference of the next shooting? Allowing no exit or enterance while the search is conducted?
Personally, I would rather position myself in line of danger to actually DO something to catch the monster than just remain positioned in danger as a sitting duck.