I just watched that movie, the girls are kidnapped not killed and rise from a pool of water near the tower to then be taken by the Hunter and placed in a crypt.
They weren't killed but in comas, with no heartbeat or breathing.
It makes sense that the drowning girl and mud/well girl spring rise from the puddle.
But the horse girl doesn't make sense.
When the horse got there, was it gutted by the Hunter? Did it vomit? Did it reverse vomit?
It's one of the main characters' horse and it disappears afterwards.