Does anyone know how red light cameras at intersections work?

[letswastemoney]

I crossed an intersection with a "red light camera" without realizing there was not any room on the other side for my car to fit, so I got stuck on the very edge within the boundaries of the intersection. I crossed when it was green but since I got stuck on the edge...I'm thinking I might get a ticket.

But how do the cameras work? Do they only take pictures if you cross while it's red? That's probably not the case, but oh well