MISHAWAKA, Ind. (CBS) — Residents of Mishawaka, Ind., were evacuated from their homes overnight when an industrial fire sent a chemical cloud over a neighborhood.

As WBBM Newsradio’s Mike Krauser reports, it was a small rubbish fire in an old metal-finishing plant, according to the Mishawaka Fire Department.

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LISTEN: WBBM Newsradio’s Mike Krauser reports

The fire sent a chemical vapor cloud into the air when it broke out Friday evening.

Nearby residents were told to turn off air conditioners and close windows, and were then told to evacuate.

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“The air is real heavy; smog in the air; a lot of moisture, and it was warm,” said fire Battalion Chief Jim Cocquyt.

Cocquyt says the plant had been taken over by the U.S. Environmental Protection Agency, and a cleanup has been underway for several months. They were not sure what was in the chemical cloud, but evacuated to be safe.

“A lot of unknowns; we’re in a building that you’re not allowed to go into. The people in charge of it were coming from the south part of Chicago and the Hammond area – the representatives from the EPA,” he said.

A few hundred people were kept out of their homes. Some spent the night as a school that had been set up as a shelter, while others stayed with friends and relatives.

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The cause of the fire is not known.