Brewers Best Kit Fermenting Like Crazy

I am trying to not pose this as a "Is My Beer Ruined" post. Just curious if anyone has run into this situation.

On Friday I brewed a batch of Imperial Pale Ale from a brewer's best kit. I used WLP001 with a 2 pint starter. I have never seen fermentation out of control like this before. I am fermenting 5 gallons in a 6.5 gallon carboy. The krausen overflowed the airlock about 5 times and has blown the cap off the carboy twice.

The first time was overnight so I didn't catch it until morning. I sanitized it and put it back on. The second time just happened. As luck would have it I was within 5 feet of it when the cap blew. I picked it up and put it back on.

Has this happened to anyone before? I have my fingers crossed that having the cap off all night without me knowing doesn't lead to contamination and a ruined batch. There's nothing I can really do about it so I'll let the cards fall where they may. Just wondering if this has happened to anyone and if so, what was the result?

Thanks!

Aggressive fermentation is pretty common and it can be pretty common place in carboys due to a less headspace between the wort and airlock. I'd recommend throwing a blow-off tube on that carboy immediately. If you're limited on home brew supplies you might be able to take a siphon tube from your racking cane and slipping it on your airlock and then dunking the other end into a large pot of sanitizer solution.
In regards to contamination you are definitely at risk of it happening, but since your fermentation has already started your yeast should help fight off any other bugs that get into the wort and the alcohol that has already been created might offer some protection.