I do remember the fire extinguisher I used had ammonium sulphate because when my brother read the list of the chemicals in the extinguisher and I heard that name, I of course remembered ammonium thiosulfate (or is it thiosulphate? either way it sounds the similar).
I thought about just leaving the oven door closed and letting the fire go out on its own, but the flames were somewhat substantial and even though ovens are meant to contain a lot of heat, but I didn't want to risk burning down the kitchen. I may be mistaken but I believe it's only a matter of time before the fire is too hot and gets through the insulation. Also, it's not my house- I live go to school nearby so I live at home and I didn't want to take a risk with their house when I didn't know whether or not the flame could go out on it's own or if it would keep burning.