ST. PAUL — The days-long scrap fire that raged at the Northern Metal Recycling site in Becker, Minn., last month started by accident, state investigators have determined.

Body and dashboard camera footage, as well as burn pattern analyses and witness statements, indicate the flames started deep within scrap metal piles they later consumed, according to a newly released Minnesota State Fire Marshal report. The fire may have been started by a spark or heated piece of metal, the report states.

Discarded batteries and water-reactive metals may have also been a factor.

"Due to this evidence, I did not find any intentional reasons for the fire starting," Minnesota Department of Public Safety investigator Casey Stotts writes in the report, dated Monday, March 9.

The Becker site fire began deep within the piles of junked motor vehicles on Feb. 18 and took days to put out. Minnesota Public Radio reported that the outermost layer of the scrap heap froze over during the battle, making the flames within that much more difficult to combat.

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As smoke from the fire poured into the air, nearby residents were told to stay indoors if possible to avoid breathing it in. Health concerns abounded as a result, although state officials said at the time that preliminary air tests did not result in any findings that would have warranted an evacuation. Groundwater near the area was also tested.

Approximately $1.5 million worth of recyclable material was lost in the fire, according to the fire marshal's report. Northern Metal moved operations to Becker after agreeing to leave Minneapolis and pay a fine in 2019, according to MPR News. Its exit followed accusations of air quality violations and fraudulent emissions reporting.

Recycling operations had not gotten underway at the Becker site by the time the fire began. The company had been stockpiling cars as it sought regulatory approval from state and local authorities.