The party has cleared the ground floor of Skyreach Castle. How does the rest of the castle react?

So my party of 6 has pretty much cleared out everything in the lower section of Skyreach - they've dealt the the cultists, Rezmir (and Frulam too - I had Frulam travelling with Rezmir), Azbara Jos & Rath Modar, and have just killed Glazhael.

I'm wondering how the upper floor (the orcs, Blagothkus, etc) will react to the dragon being killed. Glazhael let out such a roar that everyone else in the castle will have heard it, but does Blagothkus care? Do the orcs come to check whats happened? Do they fight the party if they see the dragon is slain?