Three Democratic lawmakers are asking federal watchdogs to investigate whether U.S. Park Police broke any laws in routing demonstrators from the square in front of the White House last week.

The request was made in a letter released Tuesday to the Interior Department inspector general, Mark Lee Greenblatt. Officials were in the early stages of reviewing the request, said IG spokeswoman Nancy DiPaolo.

Park Police and other security forces lobbed chemical agents and punched and clubbed demonstrators and journalists in clearing Lafayette Square near the White House on June 1, as protests surged around the country following the killing of George Floyd in police custody. Trump administration officials have denied federal forces were making way for President Donald Trump to stage photos nearby.

The request for an investigation was made by Sen. Ron Wyden of Oregon, House Natural Resources Committee Chair Raul Grijalva of Arizona, and Committee Vice Chair Rep. Debra Haaland of New Mexico.

“The First Amendment rights to free speech, peaceful assembly, and free press are the building blocks of all other rights,” the three lawmakers said. “Any actions by the Park Police to muzzle these rights is an affront to all Americans and should be swiftly addressed.”

A force of several hundred officers under Interior’s National Park Service, U.S. Park Police are charged with law enforcement at Lafayette Square, at the Statue of Liberty in New York, and at a small number of other heavily visited federal sites.

An Interior Department spokesman, Conner Swanson, called the lawmakers' accusations “an insult to the fine men and women who put their lives on the line to protect our citizens and defend America's national treasures.”

“The suggestion that the United States Park Police would ‘muzzle’ Americans’ rights is outrageous," Swanson said.

Interior Secretary David Bernhardt told Grijalva in a letter last week that the Park Police had been in a “state of siege” from violent attacks in the square.

Democratic lawmakers say witness and journalist accounts and photos and videos made public so far don’t support allegations of that scale of protester violence.

The three lawmakers’ letter, sent Monday, asks Interior’s internal watchdog whether the force used by Park Police was lawful and in line with rules, policies and training standards for the force.

Lawmakers also asked the investigators to determine who was giving orders to the Interior Department in the square’s clearing.