Gregory Monahan, acting chief of the U.S. Park Police, defended the forceful removal of protesters from a park near the White House on June 1 that immediately preceded President Trump's photo-op before a church, saying his officers "acted with tremendous restraint."

Monahan testified Tuesday to the House Natural Resources Committee that neither the White House nor Attorney General William Barr ordered the removal of protesters from Lafayette Square, and that the incident commander of the Park Police ordered the clearing because protesters had turned violent from May 29 to June 1 and more than 50 officers had been injured during that time.

Monahan told lawmakers that the park clearing – roughly 30 minutes before the planned 7 p.m. curfew – and installation of new fencing had nothing to do with Trump's walk from the White House to take a picture before St. John's Church that had been damaged by fire the night before.

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"We did not clear the park for a photo-op," Monahan said, noting his officers gave protesters three warnings. "We cleared the park for public safety."

"There was 100 percent zero correlation between our operation and the president's visit to the church," the Park Police chief added.

Acting U.S. Park Police Chief Gregory T. Monahan, testifies before a House Natural Resources Committee hearing on actions taken on June 1, 2020 at Lafayette Square, Tuesday, July 28, 2020 on Capitol Hill in Washington. He sits with a helmet of one of the officers who was injured by a violent protester who threw a brick at his head. (Bill Clark/Pool via AP)

However, Adam DeMarco, a major in the District of Columbia National Guard who was on the scene as a liaison between the Guard and the Park Police, said the three warnings on a megaphone were "barely audible" and occurred 40 minutes before the curfew was to go into effect.

DeMarco said the protesters were peaceful and were subjected to an "unprovoked" and "excessive" use of force. He said the police used CS or “tear gas" as he saw spent tear gas canisters on the street nearby. The actions against protesters on June 1 were "deeply disturbing," he said.

President Donald Trump holds a Bible as he visits outside St. John's Church across Lafayette Park from the White House Monday, June 1, 2020, in Washington. Part of the church was set on fire during protests on Sunday night. (AP Photo/Patrick Semansky)

"[I]t was my observation that the use of force against demonstrators in the clearing operation was an unnecessary escalation of the use of force," DeMarco told lawmakers. "From my observation, those demonstrators – our fellow American citizens – were engaged in the peaceful expression of their First Amendment rights. Yet they were subjected to an unprovoked escalation and excessive use of force."

DeMarco is a graduate of the U.S. Military Academy at West Point and holds a master's degree from Georgetown University. He unsuccessfully ran for Congress in 2018 as a Democrat in Maryland.

Monahan contends police were "specifically prohibited the use of CS gas on June 1." He said police used pepper balls, smoke canisters and Stinger balls on the protesters to clear the park. Monahan said he knew earlier in the day that Trump would be visiting Lafayette Square.

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The clearing of the park came as Trump gave a Rose Garden statement that he was taking action to mobilize federal resources to quash violent protests. He also threatened to deploy the military if states didn’t send in the National Guard to the protests.

"I have recommended every governor deploy the National Guard in sufficient numbers to dominate the streets," the president said during his speech. "We are ending riots and lawlessness, we will end it today."

After the park was cleared, Trump walked to St. John's Church with Barr, daughter and White House adviser Ivanka Trump, chief of staff Mark Meadows, and Defense Secretary Mark Esper. He made no comments or prayers but posed for a photo with a Bible before the church.

Democrats contended the clash with protesters – before the 7 p.m. curfew – was an unwarranted escalation and coordinated with Trump's crackdown speech and subsequent photo-op.

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Rep. Raul Grijalva, D-Ariz., said the park clearing was a "test run" for Trump's effort to send federal officers to cities nationwide like Portland.

President Donald Trump walks past police in Lafayette Park after he visited outside St. John's Church across from the White House Monday, June 1, 2020, in Washington. Part of the church was set on fire during protests on Sunday night. (AP Photo/Patrick Semansky)

"Lafayette Square was a test run for ... [an] illegal and ongoing crackdown by the Trump administration that is being inflicted on cities across this country and attempts to escalate those confrontations," Grijalva said. "Rather than deal with and admit what did occur on June 1 was wrong, the administration is doubling down on its response to unarmed civilians in cities like Portland."

But Republicans on the committee backed the police action and accused Democrats of holding the hearing for political purposes.

"Just the nature of today's title that somehow the U.S. Park Police attacked peaceful protesters is ludicrous," said Rep. Jody Hice, R-Ga. "The assertion that these were peaceful protests is completely ignoring the facts."

Monahan said the demonstrations near the White House against George Floyd's death included "bad actors" that threw projectiles at police, including bricks, rocks, lit flares, water bottles, fireworks and 2x4 sections of wood, which caused more than 50 officers to be injured – but only one officer was injured on June 1 – and that was after police started clearing the park, he testified.

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The clearing was needed to install a new non-scale fence in the area that police determined was needed to de-escalate the protests, he said.

Monahan said protesters were given three warnings to leave the park, though Democratic lawmakers and certain witnesses at the scene said warnings were not audible and they were startled to see police use force on largely peaceful demonstrators before the 7 p.m. curfew.

"The United States Park Police acted with tremendous restraint in the face of severe violence from a large group of bad actors who caused 50 of my officers to seek medical attention," Monahan said.

Chairman of the Joint Chiefs of Staff Gen. Mark Milley expressed regret for accompanying Trump during a photo-op amid the protests, calling the decision “a mistake."

Secretay of Defense Esper also took issue with the visit to the church, saying that he tries to keep himself and the military out of politics as best he can.

The ACLU, representing Black Lives Matter activists, filed a lawsuit against Trump, Barr, Esper, the leaders of the Secret Service, National Park Police, D.C. National Guard and others claiming they shouldn't have ordered the use of violence against peaceful protesters.

"Without provocation, defendants directed their agents in the U.S. Secret Service, U.S. Park Police, D.C. National Guard and U.S. military police to fire tear gas, pepper spray capsules, rubber bullets and flash bombs into the crowd to shatter the peaceful gathering, forcing demonstrators to flee the area," the lawsuit alleges. "Many peaceful demonstrators were injured, some severely, by this unprovoked attack."

Fox News' Morgan Phillips, Lucas Tomlinson and Brooke Signman contributed to this report.