NASHVILLE, Tenn. -- Two men attempting to make methamphetamine were arrested Tuesday evening after a small explosion outside a Nashville Walmart.

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Just before 5 p.m., shoppers reported a blast outside the store located along Murfreesboro Road in Antioch.

Officers arrived and found a container in a pickup truck had exploded and was leaking anhydrous ammonia.

One officer was treated at the scene after inhaling some of the gas. Another person was transported to the hospital but was released.

Part of the parking lot was blocked off for several hours as authorities cleaned up what they are calling a mobile meth lab.

Cory Ingram and Anthony Coker were arrested on drug and weapons charges.

Investigators said that when the explosion happened, the two were inside the store shopping for other ingredients needed to make meth.