Help! My cider has started fermenting!

Went on a road trip to VA this weekend with the hubby. Bought a gallon of cider that we were told was pasteurized but is clearly not. After 48 or so hours in room temperature, the plastic jug it's in expanded and it appeared fermentation had begun. The lid was about to explode off so I took plastic strip and I can hear air escaping.

So.... Do I put it in a carboy with an airlock and hope for the best, throw in some campden tablets, try and kill what it's doing and then try to restart fermentation later with my own yeast or just toss my expensive, far traveled cider?

Please help!

Apologies for the typos... I'm on my phone and the app only let me see half of what I was writing...

Put it in a carboy and let the wild ferment keep going. Don't forget to swish the plastic gallon jug to get all the "gunk" at the bottom. Let it go for about 3 months, see what happens.

Last year, I had a gallon jug start a ferment on me too. I had it in a cool garage. It turned out pretty good!

I agree with UpstateMike, just let it go wild, you may be pleasantly surprised withe results.

Also, just because it started to ferment naturally doesn't necessarily mean that the juice wasn't pasteurized. All types of pasteurization from UV, to flash, to full heat will eventually ferment. Yeast is all around us.

Thanks all! That's what we did yesterday... thank goodness we had an empty carboy. Sterilized it, poured it in... when there was about an inch left, we "swooshed" the bottle. We lost a bit of liquid though, it seems.. It only filled about half a gallon carboy. There's what looks like two small chunks of apple skins floating around in it, which probably has a little something to do with it's spontaneous fermentation.

We'll see what happens come spring!