Please answer asap!!!?

my boyfriend is 16 years old and on sick he has deppresion. yesterday he got really wound up and set fire to his net curtains in the room and it fired up he then realized what he had done and rung the fire brigade straight away and they got to it before it got really bad.and then he went in the police car last night at 10 and i havnt heard from him for 17 hour. he has a little record of robbery in the past but not anything like this. what do you fink will happen to him ?? whats chances of him being locked up?? whats most likely to happen to him for punishment??