CHICAGO (CBS) — A huge fire sparked a couple explosions overnight at a precious metals company in the Irving Park neighborhood.

The fire started around 4 a.m. at Horizon Metals Inc., a wholesale buyer and seller of precious metals on Pulaski Road, just north of the Kennedy Expressway.

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Witnesses heard at least two explosions after the fire started.

Firefighters knew no one was inside when they arrived, so they immediately began fighting the flames from a defensive position.

Crews had to transport water from other water mains, because there weren’t enough hydrants in the area, but officials said they don’t believe that hampered efforts to extinguish the blaze.

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The precious metal company also specializes in scrap metal recycling, so fire crews made sure to check for any possible chemical leaks.

“Everything’s under control at this time. We’ve got our hazmat team that’s going to check for any possible exposures and things like that, but at this time we know nothing,” Assistant Deputy Fire Commissioner William Vogt said. “There was an explosion that we believe was from propane, a propane tank. That was early on at the fire, and so that was another reason why we went defensive immediately.”

The fire was under control by 5:30 a.m., but crews were expected to remain on the scene for at least a couple more hours to monitor hot spots.

Officials said the building was a total loss. The roof collapsed in the blaze, and the interior of the building was gutted. One firefighter suffered a minor injury when he threw out his back, but no other injuries were reported.

A man who lives next door to the building, said he had water in his basement and minor damage to his siding, but firefighters were able to prevent flames from spreading to his home.

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The cause of the fire was under investigation.