More than 200 firefighters, some battling exhaustion, struggled with wind and terrain to put out a brush fire that started accidentally Monday at a Gold Coast estate in Manhasset, a Nassau County fire official said.

The fire was accidentally set about 3:45 p.m. by landscapers at the more than 400-acre estate known as Greentree, or the former Whitney estate, authorities said.

About 3 acres of brush burned, spread across a quarter-mile, said Michael Uttaro, Nassau assistant chief fire marshal.

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"The wind's been the problem, blowing around all over the place and changing directions," he said. "The guys were just trying to keep up with it.

"There was a lot of terrain -- rolling hills, open fields, deeply wooded areas -- that were very difficult to access."

One firefighter was treated for heat exhaustion and another for a broken ankle at nearby North Shore University Hospital in Manhasset, authorities said.

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Uttaro said the fire was started as landscapers mowed down brush and high weeds. They work for the Greentree Foundation, a nonprofit that owns and operates the estate.

"They were cutting the lawn on the estate," the fire official said. "Something from the lawn mower process sparked the fire. It was accidental."

Seventeen departments, some with stump jumpers and brush trucks, helped bring the fire under control after about three hours, Uttaro said.

The chief of the Manhasset-Lakeville Fire Department had to go up in a police helicopter to assess the fire, he said.

New crews had to come in to replace exhausted firefighters, Uttaro said, and all the hot spots were doused at around 9 p.m. Crews were starting to leave the scene.

No structures, including the mansion and employees' homes, were in danger, he said.

Authorities had set up an emergency command post on nearby Community Drive, near the hospital, and another one deep into the old Whitney estate, named after the family that bought several farms and built the mansion in the early 1900s.

The Greentree Foundation was set up by the Whitney family to preserve the home and to make it available for meetings for local and international charities dedicated to peace and human rights.

Uttaro said foundation officials had called authorities about the fire.