Agents with the Department of Homeland Security conducted multiple searches in Northwest Arkansas Thursday morning, authorities said.
The warrants were being served in the Springdale-Fayetteville area as part of an "ongoing investigation," said John Ahrends, Homeland Security resident agent in charge.
Police in Rogers, Fayetteville and Springdale confirmed they are assisting serving the warrants and directed further questions to federal authorities.
Bryan Cox, a Homeland Security spokesman, said the department was serving state warrants out of Washington County, and the U.S. district attorney's office for the Western District of Arkansas involved with the investigation.
Cox declined to elaborate on the nature of the investigation. The U.S. attorney's office did immediately return a request for comment.
It was not clear early Thursday if any other police departments were involved with the operations.
Read Friday's Arkansas Democrat-Gazette for full details.
Reporters Tracy Neal and Scarlet Sims contributed to this story.