The shot took one of the males on the forehead, sending the charging creature crashing to the ground as it's legs tangled.  Even if the shot hadn't killed it (for Kelbi were notoriously hardheaded) the fall crippled it at the very least and the way it lay so still on it's side told Caitlyn that it was unconscious at the very least, more likely dead.  The other two males leapt the bushes before Caitlyn managed to reload but the abandonment of her hiding place to back away gave her some room yet, space to squeeze off one last shot before they would be upon her.