This could very well be the case but I was surprised at an eyewitness account in the parking lot of Home Depot that helicopters were at the scene within seconds of the shooting. I got to believe the LEOs are close to apprehending the Killer, especially after getting what apparently is a good make on the car and perhaps the killer himself.
I so hope you're right about them being close to apprehending the killer. Question is, how many more people will he kill before becoming sloppy enough to be caught?
Regarding speed of response: Fairfax Co. has a very large and competent police force. At least, I think it's large - I see 'em all the time, everywhere I go. I've lived here two years and can probably count on my hands the number of times I've been out without seeing a F'fax Co. police officer or three. So even if there wasn't a big alert on here in the area, it's not at all surprising that Fairfax Co. would be on the scene with amazing speed.