Area firefighters responded to a late-night industrial fire Wednesday at the east end of Tamaqua.

The blaze resulted in a heavy shroud of fog and caustic smoke with a distinct chemical smell encircling the east end of town.Units from Tamaqua, Lansford, Summit Hill and other areas were summoned by a 10 p.m. Schuylkill Communications Center report of a commercial fire at Hart Metals Inc., 1415 E. Broad St.Hart Metals is a magnesium powder manufacturer that has operated in Tamaqua since 1996.An initial report suggested that all workers but one had safely exited the building. That report was updated shortly after to indicate that everyone had gotten out safely but that responders should approach the fire with extreme caution."It's reportedly a magnesium fire," warned emergency dispatchers. "Do not approach the scrubbers."Some at the scene said firefighters are required to tackle a magnesium fire with special techniques. In fact, sometimes municipal firefighters take a secondary role to in-house emergency response teams trained to use specific chemicals to quell a chemical blaze.In this case, water could not be used to fight the magnesium fire.Magnesium can be highly explosive and is capable of reducing water to highly flammable hydrogen gas.As a result, water cannot extinguish the blaze. The hydrogen gas produced only intensifies the fire. Dry sand can be an effective smothering agent, but only on relatively level and flat surfaces, according to Wikipedia, an online information source.In fact, magnesium also reacts with carbon dioxide to form magnesium oxide and carbon. For that reason, carbon dioxide fire extinguishers also cannot be used for extinguishing magnesium fires.Police and fire police kept traffic and spectators away from the area, where air quality was compromised.Just a few minutes of breathing the air at the scene was enough to irritate throats, particularly in the vicinity of the former Jamesway Shopping Center and Sisters Cantina. On the advice of officials, members of the media retreated, eventually leaving the scene altogether due to caustic air.At 10:13 p.m., Tamaqua fire police were summoned to close Route 209 at the east end of town.Minutes later, District 40, Coaldale, with its fire police, were summoned to close Number 11 Hill between Coaldale and Tamaqua.Firefighters, including RIT response teams and fire police volunteers, were seen wearing air filtration masks at the scene.Although damage assessments were unavailable, initial reports indicated that the fire affected the interior and exterior of the plant, located just east of Sisters Cantina restaurant and near the access road to Lehigh Coal & Navigation Company.Some units were released shortly after 11 p.m. when reports indicated the fire had been contained and it was being allowed to burn itself out.An all-clear was announced at 11:41 p.m. and the highway re-opened to traffic by midnight.In February of 2010, Hart Metals received $1.6 million in federal funding to develop new high-performance magnesium alloy powders for the U.S. Defense Department.The funding was secured by Rep. Tim Holden and Sen. Bob Casey. Hart Metals reportedly works closely with the U.S. Army Research Laboratory, Aberdeen Proving Grounds, Maryland, on the project.As a result, the firm has been designated a critical supplier by the U.S. Department of Defense.In January of 2000, four Hart Metals workers were injured in an explosion caused by a leaking propane tank in the main storage shed, which knocked over a wall and injured workers in an adjoining room.The cause of Wednesday's fire is being investigated.