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.

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.

“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.

The cause of the fire is not known.