BECKER, MINN. – There was one thing everyone northwest of the metro area could agree on Wednesday as a smoky haze from an industrial fire spread across the region from Becker to Big Lake to Otsego to Albertville.

"It stinks," said Derek Neumann, of Big Lake.

The noxious plume of smoke rising here from a fire at Northern Metal Recycling smelled like scorched metal and burning plastic. But residents living nearby were concerned about more than just the smell after officials warned people with respiratory illnesses to stay indoors.

"They say it's not toxic, but we don't feel that way," said Heather Yanish, a stylist at the Hair Dresser in Monticello, about 8 miles from the burn site. "We're skeptical of the 'but': 'Stay in your house, but it's not toxic.' "

Late Wednesday, Superintendent Jeremy Schmidt announced that Becker Public Schools will be closed Thursday because of heavy smoke. "This decision will allow the school district administration an opportunity to make decisions about other potential school district impacts without placing students and staff in a possible harmful or uncomfortable situation," Schmidt said.

More than 36 hours after a passerby reported the fire early Tuesday, crews from more than a dozen fire departments were still on the scene trying to tamp down a blaze that had consumed hundreds of junked vehicles and was still sending flames leaping high into the air in this Sherburne County city about 45 miles northwest of Minneapolis.

While residents expressed concerns about the quality of the air they were breathing, officials gathered atmospheric samples and waited anxiously for test results to come back.

The cause of the blaze is unknown, and Becker police said Wednesday night that it could be several more days before it's put out. In the meantime, firefighting crews were trying to separate a portion of the burning stack of vehicles in hopes that the blaze would eventually die out. The strategy was intended to protect nearby buildings, including the main source of power to the facility.

"The resulting fire will be more intense and will produce more black smoke, but the plume is expected to rise higher into the air and travel farther before dissipating," Becker police said.

A company official reached at the scene Wednesday night said he didn't have time to comment.

Northern Metal moved its shredding operation from north Minneapolis to Becker last year when the Minnesota Pollution Control Agency (MPCA) ordered it to shut down after finding high levels of air pollutants in the neighborhood that have been linked to health problems such as increased risk of heart attacks, bronchitis and asthma.

The company was fined $200,000 after it admitted to altering and inaccurately recording pollution readings.

On Tuesday, Becker officials called in a Sherburne County Emergency Management team, the MPCA and the state Department of Health amid concerns over air quality. The MPCA was monitoring the air Wednesday.

The Health Department also was consulting with other agencies on the scene, said spokesman Doug Schultz, noting that the advice to avoid exposure by sheltering in place or leaving the area is the same that would be given out in the event of a large forest fire.

An All-Hazards Incident Management Team also was called in to help with operations, Becker Police Chief Brent Baloun said.

Northern Metal also has hired a certified third-party consultant at the request of the incident management team and, per state statute, agreed to perform additional testing on air samples, Becker police said in a statement released Wednesday night.

The MPCA has not taken any enforcement actions against Northern Metal at the Becker operation, which is in the process of getting up and running, said Mike Rafferty, an agency spokesman. He said local law enforcement and fire officials are taking the lead on air quality sampling as a result of the fire and the agency had no information to report.

Crews from at least 18 departments were on the scene Tuesday night into Wednesday morning, and many were expected to remain at the Becker Industrial Park, Baloun said.

The fire burned so hot that authorities worried about depleting Becker's water supply. A steady line of fire tanker trucks ferried water to the scene throughout the day Wednesday from Xcel Energy, Liberty Paper and other area businesses.

"This type of fire, you need a lot more water," Baloun said. "The hydrants can only produce so much. You're concerned about drawing down your water to the city."

Wednesday morning, dozens of firefighters were gathered in a staging area less than 100 yards from the burning pyre. None wore hazmat suits or respirators and no one seemed overly concerned about toxic exposure.

By early afternoon, the fire still had a number of hot spots and authorities said it wasn't fully under control. Piles of scorched cars were covered with ice from the steady spray of fire hoses.

Occasional explosions could be heard, possibly caused by tires, gas tanks or car batteries. Meanwhile, equipment operators using bull­dozers, claws and loaders worked to pull apart the burning piles of wreckage.

"If anybody was watching this, they couldn't help but be impressed," Baloun said, praising the efforts of firefighters. "These guys are working their [tails] off."

Residents of Big Lake, 9 miles to the southeast, caught the worst of the drift Wednesday. In an e-mail, Big Lake Police Chief Joel Scharf said he was hoping to get more information soon about possible airborne danger.

"With a wind shift it's stronger today," Scharf said. "Our officials are very concerned about what's in the air."

Staff writer Tim Harlow contributed to this report.