State Guards in USA?

[Legbreaker]

So in the US, Guards are essentially little more than wannabes with time on their hands or emergency volunteers who may carry weapons?

That's a completely foreign concept over here in Australia. We have organisations such as the SES (State Emergency Service) which respond to car accidents, floods, lost hikers and the like, volunteer fire fighters (Rural Fire Service being one such group) and various charity groups that are involved in community work (Lions, Rotary, Returned Services League, etc), but nothing that I can think of like the description of the US Guards.

Can somebody shed more light on what they're actually for and what they can and can't do?