Fired 700+ rounds over several minutes unopposed is very likely true. Agree 10 full autos unlikely, probably semis or mostly semis, but I would attribute that to journalist idiocy rather than intentional “fake news.” But I thought the smoke detector angle was being doubted.
No, based on my experience with cooking grilled-cheese sandwiches, I would expect that a smoke detector could be set off after only a hundred or so rounds being fired.