Truly disturbing. Not much you can do, short of covering up as much as possible to protect the vitals. You WILL incur substantial injury to the extremeties, but hopefully you can protect the face, neck, etc.
Try to get away beforehand if you are able to.
"In case you ever wondered what it's like to be knocked out, it's like waking up from a nightmare only to discover it wasn't a dream." -Forrest Griffin