Should I cover or harvest my tomatoes due to a frost advisory?

We have a frost advisory for our area tonight, and I have TONS of tomatoes on the vines. I live in the city and have a smallish yard, houses close together, so I don’t think it will get as cold here as out in the farmland. Will a light frost end my tomato harvest? Should I try to cover them with sheets, harvest them green, or just leave them and hope for the best?