Unknown Ambulance Bill was sent to a Collection Agency

So something told me to randomly check my credit report and I realized the Los Angeles Fire Dept had charged me for an ambulance ride that occurred in February of 2012.

I received NO bills in the mail. I didn't see where they had tried to bill my insurance company. I didn't receive any phones etc.

I see that as of October 2012, the bill was sent to a collection agency and I owe approximately $1400. What in the....?

I'm a college student, so all of credit reporting/collection agency stuff is kind of foreign to me. I pay my bills on time and have never had issues like this before.

I would have had no problem paying the original ambulance bill HAD I or my insurance company received any requests for a payment.

What steps should I take next? What are my options? I'm outraged!