It's hard to say, but it is incredible. They may have been shallow, or little more than light punctures, but the amount could easily add up to serious if not fatal blood loss. What is a shame to me is that on some links in the story the satanic angle is played for fear and hype which can't do those in non-traditional religions like Wicca any good. They have nothing to do with Satanism, being non Christian, but for the average news watcher no great distinction is likely to be made.
The story is quite sensational enough and sad for those in it for the trouble they must have in their heads to do something like this. However, whether it was one or both girls, or the guy as well for whatever reason, and this got out of hand, all of them need help. That is not likely to come by playing up some phoney satanic cult angle that can lead to ridiculous fears.