I am sorry to hear about your loss.  Some things to look for that may help identify the predator are included in the attached fact sheet.  I would have many questions to start narrowing down the possibilities.  Where are you located (rural, residential, in woods, in open area)?  Were the chickens in a pen or free range?  If in pen, what type of damage was done where the predator entered?  Were any of the birds missing or were they killed and left behind?  Are there any prints near the birds, inside the cage, outside the cage?  With the recent rain there may be muddy prints somewhere.  How large were the bite marks?  

The most common night attacks in this part of the state are from racoon, fox, coyote, and mink.  There is a good chance whatever came last night will be back so make sure the survivor is in a safe location and put out trail cameras if you have access to any.  Figuring out what caused the issue will help prevent it from happening again if you get more chickens.