A blaze that began at the Northern Metals Recycling plant in Becker, Minn., early Tuesday morning continued to burn through the night, as fire crews requested additional support and authorities monitored air quality issues.

The city has requested assistance from the National Guard and the state Pollution Control Agency and Health Department.

Police told residents with respiratory problems who live near the plant to remain indoors or in well-ventilated areas. Several residents inquiring about air quality called police after the fire sent smoke into the air, Becker Police Chief Brent Baloun said. A passerby first spotted the fire around 2:25 a.m. Tuesday.

Crews from three departments arrived to find the fire burning in a debris pile of crushed-up cars. No one was injured and no buildings were damaged, Baloun said. It was not immediately clear how the fire started.

Northern Metals moved its shredding operation from north Minneapolis to Becker last year after the Pollution Control Agency ordered it to shut down. The agency had found high levels of air pollution in the neighborhood and that the company altered and inaccurately recorded pollution readings.