Honolulu Police Department spokeswoman Michelle Yu said detectives are pursuing leads generated from tips after witnesses told firefighters and police that several juveniles were seen running from the brush before the fire broke out on May 10.

Most brushfires in Hawai'i are intentionally set, police said, but finding suspects and witnesses in rural areas is difficult.

Police said they don't recall anyone having been arrested on suspicion of setting a brushfire.

Yu said arson detectives continue to follow up leads, as the city, state and federal government shell out thousands of dollars and expend hundreds of man hours to battle the blaze.

Fire units, with a base camp at Nanakuli High School, continue to patrol the valley looking for hot spots and potential flare-ups. Jeff Widener • The Honolulu Advertiser

"Historically, we don't prosecute brushfires because seldom do they catch anyone and it is difficult to prove property value," said Jim Fulton, spokesman for the prosecutor's office. "We may need to look at new legislation in order to charge these things."

Fire officials say brushfires have spiked recently as the wet winter months have given way to a dry summer. As of May 12, there have been 210 brushfires reported, compared with the 89 reported through May 12 last year, said fire Capt. Kenison Tejada.

Twice since Tuesday firefighters thought they had the blaze contained, only to watch the wind shift and swirl around midday, fanning the embers and causing flare-ups.

Yesterday, helicopters continued dousing the flames and crews worked to stamp out hot spots and uncover hidden patches of smoldering brush.

Tejada said the department had four engines, two tankers and Air One working the fire. About 40 city firefighters worked rotating six-hour shifts in accessible groves of green brush at the back of the valley.

Much of the fire burned up steep slopes inaccessible to firefighters, prompting the need for continuous water drops from helicopters.

Five helicopters, two from the military, two on loan from private contractors, and HFD's Air One zigzagged across the valley yesterday, picking up water and dropping it on areas susceptible to flare-ups and unreachable by foot. The water drops have been vital to containing and fighting the fire, but the repetitive nature of the mission has not gone unnoticed.

"You ever see that movie 'Groundhog Day,' where you wake up and it's the same thing over and over again? It's kind of like that," said Richard Potts, a pilot with Paradise Helicopters who has been dropping water on the fire every day, all day for a week. "You'd think we'd get a break with the wind."

Four members of The Nature Conservancy were lifted onto a slope of the valley designated as the Nanakuli Forest Reserve, where they set up a 250-gallon water tank and looked for hot spots.

Pauline Sato, O'ahu program director for The Nature Conservancy, said that the four members all shared a love of plants, and would be paying attention to the damage done by the fire.

"What's going to come in next are the invasive weeds and grasses that are going to make the next fire season even hotter and force the native forests to shrink," said Sato as she sat under a tree coordinating her team's efforts on the valley slope.

Earl Pawn, a forester with the state Department of Land and Natural Resources, said about one-fifth of the Nanakuli Forest Reserve was burned by the blaze. It was not immediately clear yesterday afternoon if the fire had crept into the Honouliuli Preserve.

Pawn said the fire came within 300 yards of three of the eight Hawaiian gardenia plants in the state.

Pawn said the terrain and conditions are still too treacherous to send in a team to determine if any native or endangered species were killed by the fire. He said that a native Hawaiian garden, built and maintained by Nanakuli High School students was partially burned by the fire.