FirefighterFag here… Building fires do NOT smell like sulfur… not even close…
Explosives, however…
I wouldn't venture to say really… There are a lot of things that could produce a sulfur smell… though none are found in a normal fire.
all i would say is it is very abnormal…
I would concede that a layperson may not be able to differentiate between the odorizer in Nat Gas, and sulfur….
…But, they are very different smells… plus the natural gas smell doesn't survive combustion.
Smoke…or Steam…or vehicle exhaust*
NP. Question Everything. My money is on if the photographer panned down, you'd see a big lit up fire engine…