We drove north to New Hampshire on instinct as soon as we had a sense of what was happening (about an hour before the formal evacuation), and saw police and firetrucks heading south the entire way. After dinner, on our way back south (not home, but to another place to stay tonight), all the highway exits in the affected areas were closed, with police at each exit offering guidance to drivers who weren't sure what to do or where to go.
The affected communities are suburban -- not in the boonies, but not urban either, and definitely not used to having to respond so urgently to a widespread problem like this. They appear to have been very well trained and ready for it.