Federal law enforcement officials raided Illinois facilities owned by construction machinery company Caterpillar on Thursday, according to multiple reports.

Caterpillar confirmed to CNBC that the company is cooperating with a search warrant targeting several of the company’s buildings, including its Peoria, Ill., headquarters.

The investigation involves three federal agencies: the Internal Revenue Service, the Federal Deposit Insurance Corporation and the Commerce Department’s Bureau of Industry and Security Office of Export Enforcement, according to Crain’s Chicago Business.

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IRS special agents were filmed entering Caterpillar’s headquarters, though it was not immediately clear what investigators are searching for.

Caterpillar stock plunged almost 6 percent by 1 p.m., nearly an hour after news of the raids broke.

President Trump hosted Caterpillar CEO Doug Oberhelman at the White House last week during a meeting with U.S. corporate chiefs.

“What a great company,” said Trump before the meeting. “I love Caterpillar. I’ve been driving them for a long time.”

Trump said he would try to visit the company soon.