A wildfire above Wahiawa grew to 75 acres Sunday from 4 acres a day earlier as state fire crews dealt with high winds and steep terrain, the Department of Land and Natural Resources said shortly before 5 p.m.

The fire was burning through native trees and ferns in the Poamoho section of the Ewa Forest Reserve, said department spokeswoman Deborah Ward by telephone.

She said the fire was only 10 percent contained despite the efforts of 13 firefighters from the Division of Forestry and Wildlife and two helicopters making water drops. They were to be joined by the Honolulu Fire Department’s Air 1 helicopter and a helicopter from Maui later Sunday, she said.

The fire spread rapidly Sunday "because of two key challenges," she said. "Strong winds are helping to spread the fire, and, second, steep terrain."

She said the land features "60 percent native forest, including koa and ohia trees and, in the understory, uluhe ferns."

A resident on Hoomaha Street said smoky conditions worsened throughout the morning and afternoon, permeating her home and making it difficult to see beyond a few neighboring lots.

The resident said "chunks of ash" also blew through the air, settling on her yard and pressing through her screen windows.

Crews were expected to continue battling the blaze until evacuation by helicopter around nightfall. Efforts were to begin anew Monday morning, Ward said.

Honolulu firefighters initially responded to the call of the fire burning about a mile above California Avenue at 4:01 p.m. Saturday. Since the fire is burning on state land, the DLNR took over firefighting duties.

HFD and DLNR firefighters were also called to a second large brush fire near the area.

The fire, reported at 3:10 p.m., burned an estimated 30 acres near the 2200 block of California Avenue.

Area homes were initially threatened, but HFD personnel beat back the flames and continue to monitor areas near the home.

One HFD firefighter suffered a non-life-threatening leg injury and was hospitalized.

Some 43 HFD personnel from 14 companies responded to the fire, assisted by firefighters from DLNR. Two DLNR helicopters and HFD’s Air 1 helicopter dumped water on both fires through the late afternoon and early evening before suspending operations for the night.

The second fire had yet to be contained as of 9 p.m. Sunday.