"Whether Luca is still alive..."
That gives it away, there's a possibility, thus, the boy is alive. Bet he's become evil though. Actually, maybe it's she even.
Now that we know what happened, yeah... the teacher was very bad to run before the students and leave them to die. But as I pointed before, the school is at fault too for not having enough people to go on a place that have a probability of monsters appearing, even if it's low.