AUSTIN, Texas (CBS SF) — An artillery simulator device injured a man at a Goodwill store in Austin, Texas on Tuesday, but investigators say it is not related to a series of explosions in the city, which authorities have attributed to a serial bomber.

The incident happened at a Goodwill store in the southern part of Austin on Tuesday evening. Austin police said it was an incendiary device that went off, and not a package bomb that exploded as in the other cases.

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Police said a box was left at the Goodwill store containing an artillery simulator device and that one person was injured.

Investigators are looking into who dropped off the device at the store.

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The Austin-Travis County EMS Twitter account said a man in his 30s was injured in this incident, but that the injuries were not expected to be life-threatening.

The bombings in the city this month have killed two people and injured four others. Early Tuesday morning, a package bomb exploded at a Austin-area FedEx distribution center. Authorities said the package bomb was sent from a FedEx office in Austin and was addressed to a home in Austin.

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A second package bomb was discovered Tuesday at another FedEx facility near the Austin airport. Authorities believe both were sent from same Austin FedEx office, which is 3.5 miles south of where the latest explosion happened and on the same street.