House Democrats want answers from the Trump administration on what happened in front of the White House on Monday, when federal law enforcement officers violently advanced on peaceful protesters, just minutes before President Donald Trump held a photo-op outside St. Johns Church.

House Speaker Nancy Pelosi sent a letter to Trump on Thursday demanding to know which agencies have been deputized by Attorney General William Barr to police the protests.

We are concerned about the increased militarization and lack of clarity that may increase chaos, Pelosi wrote Trump. I am writing to request a full list of the agencies involved and clarifications of the roles and responsibilities of the troops and federal law enforcement resources operating in the city. Congress and the American people need to know who is in charge, what is the chain of command, what is the mission, and by what authority is the National Guard from other states operating in the capital.

Her letter comes the day after four Democratic House leaders Judiciary Committee Chair Jerry Nadler (N.Y.), Natural Resources Committee Chair Ral Grijalva (Ariz.), Armed Services Committee Chair Adam Smith (Wash.) and Homeland Security Committee Chair Bennie Thompson (Miss.) demanded Trump administration officials provide Congress information about the incident in Lafayette Square, the park outside the White House.

We want to be clear: the use of federal personnel to prevent American citizens from exercising their Constitutional right to peaceably assemble represents a direct threat to our democracy, the Democratic lawmakers wrote in a letter addressed to Attorney General Bill Barr, U.S. Department of Defense Secretary Mark Esper, Interior Secretary David Bernhardt and Chad Wolf, acting secretary of the U.S. Department of Homeland Security.

Roughly 30 minutes before Washington, D.C.s 7 p.m. curfew on Monday, federal law enforcement officers in riot gear used tear gas, pepper spray, smoke canisters, stun grenades and rubber bullets to clear a crowd of peaceful protesters gathered in Lafayette Square.