Firefighters were battling a 100-acre brush fire near Keaau Beach Park in Waianae.
Ten engine companies, one ladder company, five tankers, two battalion chief, one assistant battalion chief and a helicopter crew responded to 4:55 p.m. emergency call Saturday.
No injuries have been reported but an abandoned structure was destroyed by the blaze, according to Honolulu Fire Department spokesman Capt. Robert Main.
Main said the fire was 75 percent contained as of 8 p.m. Saturday.