he fire has burned more than 100 acres of marsh grass near the Raritan Center industrial park in Edison Township.
Middlesex County Emergency Management spokesman Rob Sklans said the fire was reported at about 3:45 p.m. Wednesday.
Sklans said about 100 firefighters from Edison and surrounding towns and the New Jersey Forest Fire Service were working to contain the blaze. By 7:30 p.m., Sklans said it was about 25 percent contained.
Much of the area is inaccessible to vehicles, which has hampered the firefighting effort.
No structures were immediately threatened and no injuries have been reported.