Contaminated smoke from a burning warehouse containing farm chemicals prompted the evacuation of dozens of homes and businesses Wednesday.

A half dozen people complained of skin irritation or respiratory distress and sought treatment at a nearby hospital, said Lt. Jim Keightley, State Patrol spokesman.

Authorities evacuated a half mile area around the Wilbur-Ellis Co. (search) plant that included about 100 homes — roughly 400 people — after smoke filled the air with a strong sulfur odor, he said.

The cause of the fire was not immediately known. Officials said there was little risk of an explosion.

A hazardous materials team entered the building and set up air monitors as the fire continued to smolder Wednesday night. The Environmental Protection Agency (search) set up air monitoring equipment outside the complex to help officials decide whether additional evacuations were needed.

Shelters were also set up for the evacuees.

The warehouse stores agricultural chemicals and fertilizers, according to Ken Cowdrey, Wilbur-Ellis' head of safety in Yakima. About five people work in the warehouse.

"The chemicals are an irritant and some of them are toxic," Cowdrey said. However, he said they did not include explosive chlorine, ammonium nitrate or anhydrous ammonia.

A 13-mile stretch of Interstate 82 between Sunnyside and Prosser was closed, and officials were unsure when it would reopen.

The warehouse is on the northwest outskirts of Grandview, a town of roughly 8,500 people about 40 miles southeast of Yakima.

Students were kept inside with their schools' ventilation systems shut down to keep out the smoke, said Rachel Ott, administrative secretary for the Grandview School District (search).

Wilbur Ellis, based in San Francisco, is an international marketer and distributor of agricultural and industrial products.