The fire, which continued to smolder late Saturday afternoon well into Sunday, was on a notorious 570-acre expanse of property in Pompton Lakes considered one of New Jersey's most polluted.
Toxic substances that were dumped from what was a munitions plant on the DuPont site from 1902 to 1994 leached into the groundwater, creating an underground vapor of cancer-causing solvents.
Saturday's blaze -- dubbed the "Cannonball 2" -- covered more than 100 acres of Ramapo Mountain State Forest property and an area near Cannonball Road, according to the New Jersey Forest Fire Service.
Assisting the service and Pompton Lakes firefighters were colleagues from Wanaque and Bloomingdale, who collectively protected five abandoned structures from catching fire.
A 50-acre controlled burn was part of the firefighting strategy.
Investigators remained at work on Sunday. So did Fire Service staffers, who authorities said would monitor the situation at least until there's some significant rainfall.
No injuries were reported.
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