Cyanide - the word that strikes fear....
No one bothered to tell what KIND of cyanide the spill was. (Has a lot to do with the danger... )
Was it a truck hauling wastes, or a truck hauling new chemicals? If it was the latter, clean-up would be simple, with zero after effects.
I would HOPE the agency responding knew how to treat it.
The various cyanide compounds are quickly and easily treated - of more importance is whether it was a metal-containing compound. The metals are much harder to remove, and have a detrimental and long term effect on rivers. It is important to remove these, as well as oxidizing and decomposing the cyanide.