Oakwood, Mich. ? Hundreds of people were advised to stay away from their homes Wednesday as a fire at a suburban Detroit chemical plant sent acrid smoke over their neighborhoods.

At least 32 people, including firefighters, were treated at hospitals for breathing difficulties or burning sensations in their mouths, Oakwood Healthcare System spokesman Tom Worobec said.

Some firefighters also suffered heat-related illnesses as they fought the fire.

Witnesses said they heard several loud explosions shortly before 9 p.m. CDT Tuesday at the E.Q. Resource Recovery Inc. plant in Romulus, then saw flames and smoke shoot into the sky. The facility recycles chemicals such as airplane deicing fluid and industrial paint solvents.

The fire died down by dawn, and crews moved in with water and foam. A small hotspot burned Wednesday afternoon, according to a spokesman for the U.S. Environmental Protection Agency.

Hazardous materials officials tested the air quality and found no danger present, Romulus Public Safety Director Chief Charles Kirby said, but EPA workers were conducting more tests.