Winds are expected to diminish as emergency crews in four states continue to battle wildfires that have killed six people and destroyed hundreds of square miles of land.

The Oklahoma-based Storm Prediction Center says powerful wind gusts that fanned the flames in Kansas, Colorado, Oklahoma and Texas should ease to about 10 to 20 mph on Wednesday.

Wildfires in Kansas have burned about 1,000 square miles of land and killed one person. At least four people died in Texas, where three fires burned about 500 square miles.

Authorities in Oklahoma say a woman had a fatal heart attack while trying to save her farm from one blaze. Oklahoma Gov. Mary Fallin on Tuesday declared a state of emergency in 22 counties.

All of eastern Colorado is classified as either moderately or abnormally dry, according to the U.S. Drought Monitor.