A brush fire on Hook Mountain in Nyack Beach State Park kept firefighters at the site for more than two hours yesterday afternoon.

Volunteer firefighters from Nyack Fire Department had to battle the blaze using hand-held fire extinguishers because the fire site, about one-quarter mile up the mountain at its plateau, was inaccessible by truck, said Miles Taylor, the department's chief.

Firefighters wearing full gear hiked up and down the mountain carrying the extinguishers that were delivered partway using an all-terrain vehicle, Taylor said.

"It was the first really warm day of the year," he said.

"Any time you go up the mountain it's difficult. It could be 2 degrees, and when you've got to walk that mountain with all your gear on, I mean it was a warm day," Taylor added.

Because the burn area was so large - it measured about 150 feet by 300 feet, Taylor said - firefighters requested the aid of a helicopter to get a view of the blaze.

Rockland County Chopper One flew over the area "to give us a visual to make sure there weren't any other areas burning," Taylor added.

The fire's cause was unknown yesterday.

"The first good weekend of weather, everybody's out there hiking the trail, so I really can't speculate on how it started," he said.

The fire was reported about 4:30 p.m. No one was injured. Palisades Interstate Park police were investigating the incident, Taylor said.

Park police investigators were not available yesterday.

There was no damage to the park, Taylor said.

About 35 members from the Nyack squad and 10 members from the Congers Volunteer Fire Department were at the fire scene.