FROSTPROOF, Fla. (AP) _ A fertilizer plant caught fire on Friday, sending clouds of irritating smoke skyward and forcing the evacuation of more than 1,100 homes and businesses.

No immediate injuries were reported.

Emergency crews worried that the smoke would carry the potentially explosive ammonium nitrate that Ben Hill Griffin Inc. uses to convert phosphate into fertilizer.

The cause of the fire was not immediately known.

The blaze was expected to burn through the evening.

The chemical-laden smoke drifted over a sparsely populated area about 50 miles south of Orlando.