A “documented gang member,” who police said "should have been in prison," was responsible for a two-hour stabbing and robbery rampage in Southern California that killed four people and injured two, authorities said Thursday. Garden Grove Police Chief Tom DaRé told reporters that Zachary Castaneda "could have injured or killed many other people" had he not been apprehended as he walked out of a convenience store in the neighboring city of Santa Ana, dropping a knife and a gun he had taken from a security guard he had just killed. Police told reporters the violence appeared to be “random," with...