When Alabama was hit by the tornadoes 2 years ago, I can remember driving through areas that had signs up that looters will be shot, no questions asked. There was one case where a looter went into a gas station to steal and the owner shot and killed him. The owner was not prosecuted. There were not many problems with it, because it is common knowledge that it is not tolerated.
There must have been witnesses and the owner was an honest man. The way things seem to in NY I wouldn't be surprised if SSS goes into effect.