Dave Liquorice presented the following explanation :
Thinking that as a closed domestic door will keep fire at bay for
quite a number of minutes and block the jam and floor gap with
whatever cloth is available (wet if possible) to keep the smoke and
fumes out (the real killers). Calling 999 and sitting tight maybe the
better bet if they'll be with you in less than 10 minutes.

Back in the day when I still lived with my parents, at around 13 with a
latch key - I arrived home to find smoke billowing up just inside the
front door. A gas pipe had developed a pin hole, leaked and something
had ignited it. I was able to extinguish it by throwing water at the
burning wood work and turn the gas off.

As a result of that experience, I now have a couple of outside garden
taps fitted, with ready connected hose pipes, one at the back, one at
the side. The local village full time fire station is 1/2 mile away, so
just a few minutes.