Officials in Becker, Minn., said Saturday that the stubborn fire at the Northern Metal Recycling facility has finally been extinguished.

The fire was initially spotted early Tuesday. Over the following days, fire departments from around the state assisted local agencies in controlling the blaze as the plume of smoke drifted southeast toward the Twin Cities.

Private firefighters hired by the company are expected to leave the scene on Sunday morning, Becker police said in a news release early Saturday afternoon.

The State Fire Marshal's Office continues to investigate the cause of the fire, while the Minnesota Pollution Control Agency monitors the nearby air.

"Testing of air collected Thursday at sites near the plant shows that the air was similar to air around the state that wasn't downwind from the smoke plume that came from the fire at the plant," Becker police said.

Ongoing analysis from four air-monitoring devices near the fire scene can be accessed online from the website www.purpleair.com; click "View the Map" and then search for or navigate to Becker, Minnesota.

Crushed cars wait to be processed at Northern Metal Recycling in Becker, Minn., on Thursday. Paul Middlestaedt for MPR News

The MPCA on Friday ordered Northern Metal Recycling to stop accepting scrap metal at its Minneapolis and Becker sites until it corrects fire code violations and submits a damage assessment and a plan for storing vehicles.

The order effectively halts most of the company’s Becker operations before they could begin.

The agency’s order said that both the Becker fire and violations found at the Minneapolis site demonstrate that Northern Metal “does not have metal collecting and storage practices in place at either location that protect the health and welfare of Minnesota residents.”

Northern Metal COO Scott Helberg issued a statement protesting the MPCA’s findings.

“The company worked closely with the MPCA to obtain all necessary permitting approvals. To be clear: the Northern Metals Recycling facility in Becker has never been operational. The shredder has yet to be turned on and its installation is ongoing," he said. "Nevertheless, the facility is otherwise in strict compliance with all applicable requirements.”

Helberg said the company will be "in close contact with state, county, city and federal officials regarding this incident and its cause."