Congress on Monday began to investigate tactics used by federal law enforcement officers to clear protesters near Lafayette Square ahead of President Trump’s photo op in front of the pale yellow facade of St. John’s Episcopal Church.

Protesters, journalists and witnesses who were caught in clouds of chemical irritants, hit with police batons, pelted by projectiles and shoved with riot shields described their experiences and injuries to lawmakers, whose confidence in police officers’ tactics seemed to splinter along party lines.

The hearings before the House Natural Resources Committee were the first of several, with lawmakers signaling they have more questions about the types of weapons used and whether federal police officers issued verbal warnings before launching stun grenades and chemical irritants into the crowd.

None of the witnesses heard verbal warnings issued, they testified. But in a letter to lawmakers, Park Police said three warnings were given — using a crowd control device known as LRAD, a Long Range Acoustic Device, for conveying critical information across large distances. The device, often used to order evacuations during natural disasters, also can emit sounds at a decibel and frequency so unpleasant that it can disperse crowds.

No members of the Trump administration were called to testify. Park Police officials, who led the charge against protesters on June 1, declined to attend, lawmakers said, because one protester called to speak is part of a federal lawsuit alleging the administration authorized an “unprovoked and frankly criminal attack” on demonstrators engaging in their First Amendment right to protest.

Republican lawmakers played several videos featuring property destruction — including protesters toppling the statue of Albert Pike, a Confederate officer, from its pedestal near Judiciary Square, on June 19. They pointed to such incidents as evidence the demonstrations were not “peaceful” in nature — although many happened long after June 1.

George Washington University law professor Jonathan Turley, who was called to testify as a legal expert, said that although federal law enforcement officers probably had the right to clear the park, it is less clear whether the manner they chose was lawful.

Less than an hour before the District’s 7 p.m. curfew — instituted as a response to looting and arson around the city amid demonstrations on previous nights — hundreds of protesters were gathered on H Street NW. Journalists, clergy and humanitarian volunteers passing out water and masks to protect against the still-raging coronavirus wandered through the crowd as Park Police and National Guard members, wielding shields that said “Military Police,” lined up behind barricades.

Protesters chanted in unison and held signs aloft. Some played music while others danced and bopped in place. At least one person brought an easel to paint the scene.

About 6:30 p.m., after Attorney General William P. Barr was seen walking through the park, officers began to move closer.

Chaos broke out as federal officers charged down H Street, pushing demonstrators eastward with shields and batons. Law enforcement fired rubber pellets at fleeing demonstrators, released caustic gas and threw exploding stun grenades into the crowd.

Protesters fled from officers advancing on foot and horseback — many still holding their hands up, shouting, “Don’t shoot!” Others wretched, choking on clouds of chemicals in the air. Many pulled off masks as they coughed and wiped away tears.

For some, the chaos played out on split-screen television broadcasts as the president strode to the front of St. John’s Episcopal Church and delivered remarks for a gaggle of cameras.

Kishon McDonald, a Navy veteran who joined the June 1 protest after taking his daily run, testified that the protest was peaceful and calm when officers began to advance and fire into the crowd. He recalled feeling something explode near his ankle as he and others retreated from the line of police.

“It was excessive force,” said McDonald, who compared his experience at the protest to being subjected to tear gas during military training exercises. “We weren’t prepared for that. They shouldn’t have used [tear gas] on protesters — they’re not soldiers.”

Australian journalist Amelia Brace testified that she and a colleague cried “media” as officers punched their camera and shot at them with rubber bullets. Turley told lawmakers that the incident, which was caught on video, appeared “entirely unjustified and unlawful.”

Democratic lawmakers pointed to Trump’s remarks as the reason law enforcement officers had deployed such aggressive tactics, but Republicans said the timing was a coincidence — the U.S. Secret Service had for days been planning to install a large fence along H Street that wrapped around Lafayette Square, and officials needed to clear the area.

Gregory T. Monahan, the acting Park Police chief, issued a statement earlier this month that detailed incidents in which he said more than 50 officers were hurt during protests, which began May 29.

Monahan said protesters had thrown “projectiles, including bricks, frozen water bottles and caustic liquids” at officers. At Monday’s hearing, Republican lawmakers said some protesters had thrown bottles of urine at police and shot off fireworks during demonstrations.

Monahan has said Park Police did not use tear gas to disperse the crowd.