2002 Ford Windstar Alternator?

This morning I turned the key to the Windstar and I heard a short buzz, the lights went on the guages pinned to the right. I took the key out and the guages still pinned and eventually went down. The headlights stayed on a very dim. dim light. Later I tried it again same thing. When I turn the key to pre-ignition, the battery seems to be very weak.
I think the alternator went, and zapped the battery of any reserve . I never saw guage needles pin so fast , stay and then go down.
The van will have to be towed to the local dealership. What do you think?
Thanks.