I found that out the hard way... Not trying to save anyone, but we had a fire in the house in 1988, and I knew enough to want to rush into the house and slam all the interior doors to slow the fire, which I did, but I got burnt lungs and have scar tissue to this day from that. You can't see heat, and you can't see poison gases. You should have heard the lecture I got from the fire captain when they were writing the report!
Charles