Authorities in Florida say a woman was caught attempting to make a nail bomb with materials inside a Walmart.

Emily Stallard, 37, was spotted by a security guard roaming the aisles of Walmart in Tampa Bay.

After watching Stallard open unpaid items, including flammable materials, projectiles and matches, a security guard called the Hillsborough County Sheriff’s Office and notified an off-duty Florida Fish and Wildlife Conservation officer who was inside the store.

An arrest report cited by the station says the woman filled a mason jar with fuel, denatured alcohol and nails. She then attempted to light the bomb with a shoelace as a wick before the off-duty officer and security guard stopped her.

Deputies arrived on the scene and arrested Stallard.

“This woman had all the supplies she needed to cause mass destruction at her disposal,” Sheriff Chad Chronister said. “Had it not been for an alert off-duty law enforcement officer and a watchful security staff at Walmart, she may have followed through with her plans to cause an explosion inside the store.”

Investigators said a child, her son, helped Stallard make the device.

“The defendant encouraged the child to engage in an act that could have caused great bodily harm and induced the child to become delinquent,” the arrest report says.

Stallard is facing multiple charges, including attempted arson, fire bombing, contributing to the delinquency of a minor, child abuse and battery on an officer.