An explosion at a Volusia County business early Tuesday may have been caused by an ammonia leak, investigators said.

It happened around 3:30 a.m. at a Reddy Ice in the Airport Industrial Park, just south of New Smyrna Municipal Airport.

Hazardous materials crews shut down the industrial complex as they cleaned up the scene. The complex has since reopened.

According to New Smyrna Beach fire Chief David McAllister, a police officer was conducting his regular beat check Tuesday morning, when he said he smelled the unmistakable odor of ammonia.

The officer then drove down Industrial Drive and saw the doors blown off the Reddy Ice building. That's when he called in the fire department.

McAllister said his crews searched the perimeter of the property, but found no massive ammonia cloud or any huge buildup of the gas, though they have smelled it off and on in the area.

The fire chief said if there's a bright spot to all of this, it's that there are no homes anywhere near this site. It's strictly an industrial complex.

McAllister said he believes crews simply need to go in and shut a valve. They will then let the winds take care of the rest, as far as cleaning out what ammonia may be left in the area.

No one was in the building at the time of the explosion, which investigators said apparently happened well before the police officer drove by the industrial park.

An engineer and representatives from Reddy Ice have also arrived at the scene to help crews as needed.

How ammonia is used to make ice

Ammonia is a common way ice is produced. In some of Reddy Ice’s facilities, they utilize approximately 38,000 pounds of anhydrous ammonia as a refrigerant for ice manufacturing and storage.

Anhydrous ammonia is widely used in industrial refrigeration applications and hockey rinks because of its high energy efficiency and low cost.

Liquid ammonia is boiled and vaporizes. Its temperature drops to -27 F and makes the inside of the refrigerator cold. The cold ammonia gas is sucked up by the compressor, and the cycle repeats.

Ammonia is used less frequently in commercial applications, such as in grocery store freezer cases and refrigerated displays due to its toxicity.

Reddy Ice, a national company with plants in 31 states, according to its website, is the largest manufacturer and distributor of packaged ice products in the United States.