Ok, the chickens were not in a secured area. The first thing that I would do is to secure the coop so that no predator can get inside...this means 1/2" hardware cloth/screen or smaller over all openings...no loose boards or tin that something could squeeze through...no doors left ajar. Raccoons and possums can get through small openings of only a couple of inches. Seal it tight. Make sure the doors can be closed and *locked* with a couple of latches...something that a raccoon can't open...they can open simple latches.
The next thing I would do is to lock the chickens up in the evening when they go to roost and let them out the next morning. This takes time and energy.
Once the coop, which is the last line of defense, is squared away, then start working on the run...making it first predator proof from the bottom and sides from 4-footed predators and hopefully eventually protected from above from feathered predators.
Get them a safe place to roost and go from there. Unfortunately, if their living area isn't secure chickens usually end up being some predators meal or chew toy...they are at the bottom of the food chain.
Creating a safe environment takes work and energy and time...
Best wishes,
Ed