WOW!! same thing happend to me not long ago, but with nine of my chickens!!
I dont think it was a ratcoon that set off the trap , it was definatley a cat if you have one, I have very smart ferral cats doing that.
And if you have any coons around, I've trapped lots of those by my coop, in four nights I trapped three of them, with the trap in the same place the whole time....behind my coop, make sure you keep your traps out for more then just one night, you could find a solution! Also, if you have a day problem.... I might be able to help, HAWKS, I have hawks, terky voltures, and big birds like that!
someone on another site sugested something really cool, she built her coop, (with a run) and put net over the run so no bird preditors could get in...... I thought this was cool! oh, and if you dont have a run and decied to build one....make sure nothing can dig under it and get to the chickens, like a snake!
I hope this somewhat helps!!!!