Awww, sorry to hear that. Poor old thing was probably too slow to escape in time.
There's trashy people everywhere. Some years back two small dogs burrowed into my garden under a fence and mauled one of my cats horrendously, the screaming was terrible to hear. I had to get him euthanised, he was so mangled. He was old, nearly deaf, poor eyesight, arthritis. Probably caught him sleeping under his favourite bush.