Thank you everyone for all your helpful advice.
We have now secured the coop better and have added to it, and my 5 remaining chicks ( now 10 weeks old ) are growing very well now that we have trapped the cat, (yes it was a CAT) and this animal has been taken to the shelter.
We have now added...
A cat comes in to my garden and kills my chickens, has even opened the coop and killed 1 and tried to kill another. I don't know what I can do.... please can anyone help...