Tal,
Thanks for reporting it here.
Now that we are forewarned, if any of us gets a similar unexpected knock on the door, here's a suggestion:
Answer the door with camera or camera phone in hand. If solicited, snap a photo, then decline the offer. If you don't feel threatened, follow them to their vehicle and snap a photo of their license tag.
I suspect they will leave without bothering any of your neighbors. I'd still report it to Community Watch.
The other option is to hold them down 'till Gracie, Red and I can come over and beat the crap out of them. 