Route 206 near the White Horse Pike in Hammonton and Tuckerton Road in Shamong were closed at 7 p.m. to allow firefighters unimpeded access to the fire.
The state Forest Fire Service had classified today's fire danger as low.
The Wharton State Forest in the Pine Barrens encompasses parts of three counties: Burlington, Camden and Atlantic. The fire was near Atsion Lake and the Atsion Ranger Station, which is off Route 206 near Shamong Township.
Barresi said he did not know how large the fire was, and the cause was still under investigation.
Thunderstorms, which could bring high winds, and an expected sea breeze could complicate the firefighters' task, Barresi said.
A headquarters was set up for the firefighters at the Atsion station.
The fire was in an area that had burned in the 1980s, so there was not as much brush and vegetation to fuel the blaze, Barresi said.
No homes or other structures were threatened, he said.
"It's just a matter of getting into it," Barresi said. "It's always a problem of access."
The Wharton State Forest is the largest single tract of land in the state park system. It is also home to Batsto Village, a Pine Barrens village of 33 historic buildings, including mills, homes and a general store.
A wildfire earlier this year in the Pine Barrens of Ocean and Burlington Counties burned 18,000 acres and forced 6,000 people to evacuate their homes.
That fire was sparked by a flare fired from a military jet on a training run at the nearby Warren Grove Gunnery Range.
Contact staff writer Troy Graham at 856-779-3893 or firstname.lastname@example.org.