Gusty tradewinds quickly spread a brush fire, blackening about 20 acres by midday today in Laupahoehoe, Hawaii County fire officials said in a news release.

Fire investigators were unable to determine the cause or origin of the fire that consumed 10- to 12-foot tall grass on vacant land on Papaaloa Road at the Ochiro Road intersection.

Fire officials said the winds were blowing at 25 to 35 mph.

The first alarm was at 10:43 a.m., and the first unit was on scene at 11:03 a.m.

Ten personnel responded to the blaze. The fire department also used a helicopter.

Firefighters brought the blaze under control at 12:30 p.m., and will monitor it throughout the night.