EVA, Fla. (AP) -- A 2,100-acre wildfire burned in central Florida on Thursday, threatening 900 homes and sending dense smoke and ash into the area for a second day.

Residents of a subdivision about 20 miles southwest of Orlando were under a voluntary evacuation notice. It was not immediately known how many residents had left.

The fire began Tuesday after a tractor-trailer crashed into a power pole and ignited surrounding brush.

Helicopters, air tankers and about 150 firefighters and volunteers were working to contain the blaze.

The fire has moved into a swampy area, where it likely will burn 4,000 acres of dry underbrush before it dies out, fire officials said.

``It will smoke and smolder in this area for months and months,'' said Wayne Jones, incident commander with the Division of Forestry. ``Our biggest priority now is protecting those homes.''

Meanwhile, Gov. Jeb Bush issued an executive order Thursday putting Florida residents and agencies on alert, saying that the danger of wildfires threatens the state with a ``major disaster'' because of dry weather conditions.

The Division of Forestry said that 601 wildfires have burned in Florida and more than 16,000 acres have been consumed since Jan.1.

``That number is not normal; it is high,'' said Paul Palmiotto, assistant chief of the department.