The suspected bomb prompted evacuation of 40 families and the shutdown of traffic on the nearby Mississippi River.
State police bomb experts and the FBI were called to the scene near the town of White Castle in rural Iberville Parish, south of Baton Rouge.
Iberville Parish Sheriff Freddie Pitre said the sticks were in a box of office supplies, which had been under the secretary's desk since it was delivered a month ago.
"It's probably a dud, but you can't be too careful," he said.
Stanley "Jackie" Jackson, emergency operations director for the parish, said a clock was attached to the sticks, but Pitre said no one at the plant had mentioned that.
Pitre said the secretary found the sticks when she reached into the box for some toner for an office machine. The size of flares, the sticks were wrapped together with wires sticking out
The plant, a natural-gas pumping station, is near the Mississippi River and the Coast Guard confirmed that river traffic in the area was shut down.
The worker opened the package and called the sheriff's office around 9:40 a.m. local time. Evacuations started about five minutes later, Jackson said.
White Castle is on the south side of the Mississippi between New Orleans and Baton Rouge, an area sometimes referred to as the "chemical corridor" because of its numerous oil refineries and chemical plants.
Jackson said an area within one-half mile of the pumping station was evacuated. A shelter for evacuees was opened at White Castle school and The American Red Cross was assisting, Jackson said.
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