Celluhh

Something scary just happened. Ok not really but to me it was. The knob on our cooker hop somehow just malfunctioned. It was already kind of not working properly but when my grandma tried to use it to turn off the fire it suddenly couldn't work. I wanted to use the fire extinguisher we had at home to extinguish the fire but my dad said I can't cos even though the fire is extinguished the gas particles are still present and this makes it even more dangerous. I want to ask if he is right and if so , why?o