If you're flustered, just ask a couple of questions to the editor or other paid-up journos in the newsroom - it's what they expect. And your writing will be meticulously sub-edited before it goes live, and nobody will be expecting you to come out with an exciting story of scandal and corruption - they'll be fine with you phoning the council and talking about snow preparedness, or anything else you can come up with.
I would guess they're trying to test your initiative by throwing you in at the deep end. Ask experienced people for guidance and I'm sure you will receive it.
