The Department of Homeland Security said the federal immigration enforcement operation was focused on cracking down on the sale of counterfeit goods and involved agents from ICE, the FBI and the ATF. It's unclear how many vendors were detained, but DHS said at least one protester was arrested for allegedly assaulting a federal officer.

A spokesperson for the Department of Homeland Security said the agents were conducting an enforcement operation against sellers of "counterfeit goods."

A female witness told NewsNation other protesters were being arrested for “simply standing and using their First Amendment right to protest.”

Markets were slow to gain traction early Tuesday as investors awaited a raft of the latest corporate earnings reports. Futures for the S&P 500, the Dow Jones Industrial Average and Nasdaq were all effectively unchanged before the bell.

U.S. stocks headed lower in Wednesday's final hour of trading, with the Dow Jones Industrial Average and S&P 500 poised to end a three-day stretch of gains.

The pressure is on companies to show that their profits are growing following a torrid rally of 35% for the S&P 500 from a low in April.