ANDERSON, Ind. (AP) -- A magnesium recycling plant's sprinkler system helped turn a small fire in a scrap bin into a toxic inferno that forced thousands of people from their homes, fire investigators said.
Officials are trying to determine why the Advanced Magnesium Alloys Corp. plant had a working sprinkler system in the same area where the metal is stored. Water causes burning magnesium to flare up and explode.
After magnesium in a scrap bin caught fire Friday evening plant workers immediately tried to put it out with dry material, said Anderson Deputy Fire Chief Mike McKinley.
``Before they could put it out, the sprinkler went off,'' he said Saturday.
The water helped fuel the burning magnesium, which by Friday evening forced the evacuation of about 5,000 nearby residents because of hazardous fumes. Those residents were allowed to return home Saturday after the fire subsided.
Officials said the plant's sprinkler system was installed when the building was the General Motors Delphi Engine and Energy Facility.
Connie Smith, a spokeswoman for Anderson Mayor Kevin Smith, said fire officials told plant officials 18 months ago to cap the sprinklers. Capping the sprinkler would have been easier than removing it, which would have required a zoning variance, she said.
No one was answering the company's phone Sunday.
Detective Terry Sollars of the Anderson Police Department said fire investigators continued their work Sunday to assess the sprinkler system's role in the fire. They were also trying to determine how the fire began.
He said the fire continued to smolder Sunday but was essentially out.
Officials were uncertain how much of the 300,000 pounds of magnesium stored in the plant for recycling burned in the fire.
McKinley said that before officials do anything else, they will remove 800,000 pounds of already recycled magnesium slabs from the burned building.
The U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives was at the site to try to determine the fire's cause and origin, said agent Mike Vergon.
Anderson is about 35 miles northeast of Indianapolis.