No, I'm saying they were on the access road just outside the lot. The witness account that they were "near the entrance" could mean the back parking lot entrance, behind Fortune restaurant, which certainly puts them on the access road.
Go 100 yards to the end of the access road, there's a stop sign, not a light. Make a right onto Patrick Henry, drive 200 yards, and you're at the Rt. 7 light. Make a right, and you're headed back to Seven Corners. A left, and you're headed toward Bailey's Crossroads.
The right takes you to more traffic, more lights, more complication, the horrible Seven Corners intersection (not to mention right back to the scene of the crime). The left puts you on on a straight shot down Rt. 7, enough traffic to blend in, but not enough to impede your progress. And as another poster mentioned, plenty of places to turn off if you get skittish.
These shooters seem to be very meticulous (almost diabolical) in choosing escape routes. By process of elimination, Rt. 7 east seems to me most likely.
They know from Friday they have only a few minutes (5? 10? 15?) before the police begin swarming the area and installing roadblocks on all major roads. So where did they stop?