LITTLE EGG HARBOR TOWNSHIP - Firefighters battling the blaze raging through the Pinelands of South Jersey are watching with concern to see whether thunderstorms forecast for later today will bring the relief they need - or perhaps make the massive fire even worse.

So far, the blaze has burned almost 20 square miles - an area slightly smaller than Manhattan - and the flames are only about 30 percent contained.

Officials say they don't have the manpower or resources to stop the fire on their own.

"The fire won't be out until Mother Nature helps us," said Maris Gabliks, chief of the New Jersey Forest Fire Service.

Although the forecast called for thunderstorms this afternoon, there was no guarantee that they would offer help.

"If we don't have rain, we still have the wind associated with thunderstorms, and that is scary," Gabliks said.

The fire has destroyed five houses and damaged at least a dozen more in Ocean County, and about 2,500 houses and 6,000 people were evacuated yesterday along the border of Ocean and Burlington Counties.

Although some people have been cleared to return home, more than 700 people remained in temporary shelters this morning, many of them senior citizens at Southern Regional High School, officials said.

No injuries were reported.

The fire, which started yesterday afternoon, has consumed about 14,000 acres of brush and forest in the Pinelands, the worst destruction there in six years.

The blaze likely started during bombing training at the Warren Grove Gunnery Range in Bass River Township, according to the New Jersey Air National Guard.

A spokesman for the guard said a flare used in the training might have flown off course in yesterday's high winds and sparked the fire. Conditions in the Pinelands have been dry.

Overnight, firefighters conducted two successful controlled burns of underbrush and other flammable material along the Garden State Parkway to contain the fire, said Forest Fire Service spokesman Willie Cirone.

Firefighters continued to set those fires today.

"You fight fire with fire, as they say, and that's what we have to do with this fire," said Lisa Jackson, the commissioner of the state Department of Environmental Protection.

Routes 539 and 72 are closed, as well as the Garden State Parkway between mile markers 58 and 63 in both directions due to low visibility from heavy smoke.

Fire service officials said that they expected the fire to consume 17,000 acres before it was extinguished, but that they had no idea when the fire would be brought under control.