CHICAGO (CBS) — Federal law enforcement officials on Thursday executed search warrants at three Caterpillar locations, including the corporate headquarters in Peoria.

Caterpillar spokeswoman Corrie Heck Scott said Caterpillar was cooperating with the investigation.

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“Law enforcement is present in various Peoria-area Caterpillar facilities executing a search warrant,” she said in an email.

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The U.S. Attorney’s office for the Central District of Illinois confirmed search warrants were executed at Caterpillar locations in Peoria, East Peoria, and Morton.

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Federal prosecutors would not comment on the nature of the investigation, but said the search involved agents from the IRS, FDIC, the U.S. Office of Inspector General, the U.S. Commerce Department, and the Office of Export Enforcement.