Big Wind - The most powerful fire engine of the world: 2 MIG-21 jet engines mounted on a T-34 tank base
It's for extinguishing oil well fires, owned and developed by MOL, the Hungarian oil conglomerate. It was used in Kuwait after the Kuwait-Iraq war, here is a video of it in action: https://www.youtube.com/watch?v=uyGDxglTVgA
It's still in use and maintained, the base was replaced with newer tank recently, as it was hard to find replacement parts for such an old model.
I was going to correct you where you say "3000 litres of jet fuel as I was thinking water would be better for spraying! Then I remembered about the jet engines .. 😅
Actually water is used only for cooling the surroundings. The fire is extinguished by the air current, the same principle as you blow a candle, but at a different scale, it would work without water, but the heat could reignite the gas.
Water is piped from local reservoirs. This was a problem in Kuwait, where oil wells are in the desert. The advantage of this design was it uses much less water than other fire engines.
I saw this thing work in the documentary about the Kuwaiti oil fires the first time I ever went to an IMAX theatre. For some reason that has stuck in my mind for nearly 30 years.