They were slaughtered?

[one chick]

I am so sorry for your loss. It's heartwrenching to come home to such a scene.

Honestly, the current set up is vulnerable to pretty much all predators except maybe stray domestic dogs and cats. Raccoons are the most likely culprit, being very common in both rural and suburban/urban areas. Birds of prey usually only take one at a time.

There's nothing wrong with waiting until spring to get more chickens, but whatever got your girls isn't going to be dissuaded for long by a lack of chickens so some security updates are definitely in order.

Like everyone else has suggested, 1/2" hardware cloth is the gold standard for predator protection. That will keep out everything except mice. If cost is an issue, most people can get by with only doing the lower 3-4 feet as long as the coop is secure and chooks are locked up tight at night. That is usually enough to prevent predators from reaching through the fence and grabbing birds. In your case, you can probably get by with 1x2 wire fencing for the top. But personally I would look into a solid roof like polycarbonate, fiberglass, or metal roofing panels. Regardless of what you choose to put on top you'll want sturdy supports, otherwise wet leaves or snow could cause it to collapse.

THank you for your excdellent advise. Come spring I will regroup my coup!