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 625 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.

The order issued Tuesday allows Oklahoma's state agencies to make emergency purchases needed to deliver necessary resources to local jurisdictions and is the first step toward possibly seeking federal assistance.

Fallin's office said in a news release that up to 465 square miles have burned in Beaver, Harper and Woodward counties in northwestern Oklahoma and the Oklahoma Panhandle. The release says dangerous fire conditions are expected to continue through Wednesday. Counties included in the declaration range from the Panhandle across the northern tier of the state from northwestern to northeastern Oklahoma.

The order is in effect for 30 days and can be amended to include additional counties, if necessary.

1 of 3 Texas wildfires now contained

Officials say one of three wildfires in the Texas Panhandle is now 100 percent contained.

The Texas A&M Forest Service says a fire measuring about 46 square miles near Amarillo was fully contained by late Tuesday afternoon.

Another fire that's burned more than 492 square miles in the northeast corner of the Panhandle near the Oklahoma border is 50 percent contained. It's destroyed two homes.

A third wildfire south in Gray County and measuring nearly 145 square miles is 25 percent contained.

Phillip Truitt, a spokesman for the Texas A&M Forest Service, says his agency has confirmed three firefighters were injured battling the blazes. All have been released from hospitals.

Truitt says the death toll in Texas remains at four: three deaths in Gray County and one in Hemphill County.

Part of Florida's Alligator Alley closed

The Florida Highway Patrol says a portion of Interstate 75 that's also known as Alligator Alley is shut down due to smoky conditions from a wildfire.

Lt. Gregory Bueno said in an email early Wednesday that motorists should seek alternatives routes on the highway that runs between Naples on Florida's Gulf Coast to the Fort Lauderdale area on the Atlantic Coast. It's the major east-west route across southern Florida.

The road was closed Tuesday after smoke from a 6,000-acre brush fire in Collier County caused poor visibility.

Bueno says troopers are continuing to monitor conditions.

Florida Forest Service spokeswoman Samantha Quinn tells the Naples Daily News ( ) the fire has destroyed two homes in eastern Collier County. No injuries were reported.

Residents of several nearby communities, including recreational vehicle parks in Naples, have been evacuated.

The cause of the fire remains unclear.