<< no they didn't. The gravel was to let them move in big machines to clean up the rubble without turning the grass into a big muddy mess. This is just a guess but i would bet that all of the fuel burned up in the fire after the crash.
I'll take your word if that then, my reasoning was because after a serious car accident one of the first things the police/fire service do is cover the crash area in sand to soak up any leaked petrol. >>
He is correct about the reason for the gravel, but in my experiences police/fire/ems dont use sand for this, they have specialized machines and materials. While Im not a firefighter or a cop, I've gone on plenty of ride-alongs (even with a haz-mat team) and I've never seem them simply pour sand over spilt fuel. I've seen them use absorbant bags similar to sandbags but even then I dont think it was sand.
I have a picture of a haz-mat team cleaning up a diesel spill but my fileserver died this morning. I'll try and get it up and running and then post a picture of what they were using.