Homeland Security Investigations, a division of the Department of Homeland Security, conducted the raid, according to Fox News.
The Department of Justice, in a statement to Fox News, confirmed the operation: "Today in the Washington, D.C., area, Homeland Security Investigations executed a judicially authorized search warrant secured by the Department of Justice." The statement said the action was "part of an ongoing federal investigation," but it did not name Omar or describe the allegations.
Omar, who was born in Somalia and brought to the United States as a child, has been a target of criticism by President Donald Trump.
The raid comes less than a month before November's midterm elections. Omar is seeking another term as representative for Minnesota's Fifth District.
CNBC said it had sought comment from Omar's office and the Justice Department. This is developing news.