Originally Published: 27 JUL 21 05:17 ET

Updated: 27 JUL 21 11:05 ET

By Clare Foran, Jeremy Herb and Lauren Fox, CNN

(CNN) -- The House select committee investigating the January 6 attack on the Capitol kicked off its first high-profile hearing Tuesday with harrowing testimony from officers who experienced firsthand the violent events of that day at the hands of a pro-Trump mob.

The committee heard gripping and emotional accounts from four officers -- DC Metropolitan Police Officers Daniel Hodges and Michael Fanone and Capitol Police Officer Harry Dunn and Sgt. Aquilino Gonell -- and will use the testimony as a jumping-off point for embarking on a probe that could lead to seeking testimony and documents from the former President, his aides and even Republican members of Congress.

The officers described the horrors they witnessed and endured as rioters stormed the building after Trump incited them to do so.

"The physical violence we experienced was horrific and devastating," Gonell told the committee. "My fellow officers and I were punched, kicked, shoved, sprayed with chemical irritants and even blinded with eye-damaging lasers by a violent mob who apparently saw us, law enforcement, officers dedicated to ironically protecting them as US citizens, as an impediment to their attempted insurrection."

"The mob brought weapons to try to accomplish their insurrectionist objectives and used them against us," Gonell said. "These weapons included hammers, rebars, knives, batons, and police shields taken by force as well as bear spray and pepper spray."

"I was particularly shocked at seeing the insurrectionists violently attack us with the very American flag that they claimed they sought to protect," he said.

The hearing started with a warning from Democratic Chairman Bennie Thompson that "we cannot allow ourselves to be undone by liars and cheaters," while GOP Rep. Liz Cheney, one of two GOP members on the panel, called for prompt enforcement of subpoenas.

"The task of this committee will require persistence," Cheney said in her opening remarks. "We must issue and enforce subpoenas promptly. We must get to objective truth. We must overcome the many efforts we are already seeing to cover up and obscure the facts."

At the start of the hearing the committee showed video footage with graphic content depicting the violent storming of the Capitol.

"These rioters were organized. They were ready for a fight ... they came close to succeeding," Thompson said in his opening statement. "It's frightening to think about how close we were. A few inches of wood and glass. An officer turning left instead of turning right."

As he denounced the "Big Lie" spread by former President Donald Trump that the election was stolen, Thompson said, "We know that efforts to subvert our democracy are ongoing, and a major part of the Select Committee's work will be to find ways to eliminate that threat."

The emotional testimony marks the start of the committee's investigation into the circumstances surrounding the attack as Democratic leaders look to set the tone for a panel that congressional Republicans have dismissed as a political sideshow created merely to discredit the legacy of the former President.

The goal Tuesday, according to select committee member Democratic Rep. Adam Schiff of California, is to portray what it was like "to be on the front lines for the brave police officers" and to push back on efforts to whitewash the events of that day.

"I'm hoping that the hearing will give the American people an even more vivid sense of what went on that day, the horror of that day, how these brave police officers saved so many lives," Schiff told CNN.

But the hearing will be just the beginning. In the weeks ahead, the panel of seven Democrats and two Republicans, all appointed by House Speaker Nancy Pelosi, will contend with how they can make the biggest impact, how to choose which documents to seek and, perhaps most importantly, to decide whether they will try to force Trump -- as well as some of their Republican colleagues who spoke to him that day -- to testify.

Democrats had pushed for an independent commission to get to the bottom of how pro-Trump supporters breached the Capitol in a deadly riot, attacked police officers and disrupted the certification of Joe Biden's November election win. After Senate Republicans blocked the commission, House Speaker Nancy Pelosi moved forward with a select committee.

Cheney said in her opening remarks, "On January 6th and the days thereafter, almost all members of my party recognized the events of that day for what they actually were," and "No member of Congress should now attempt to defend the indefensible, obstruct this investigation or whitewash what happened that day."

Pelosi has sought for the select committee to be able to provide an exhaustive accounting of the events surrounding the attack, the former President's role, how extremist groups were able to organize and how security failures resulted in the deadly clash. But the California Democrat has also taken steps that have infuriated House Minority Leader Kevin McCarthy, including shutting down two of his picks for the select committee because of their past statements and actions that bolstered Trump's false narrative about the election being stolen.

Pelosi named Cheney to the select committee, and after she rejected Reps. Jim Jordan of Ohio and Jim Banks of Indiana, McCarthy pulled the rest of the Republicans from the committee. Pelosi responded by adding Rep. Adam Kinzinger, an Illinois Republican, to the panel, in an effort to give it bipartisan credibility even without McCarthy's participation.

In a show of the importance of the Republicans serving on the panel at Pelosi's request, Cheney will give an opening statement after the select committee's chairman, Democratic Rep. Bennie Thompson of Mississippi.

Cheney and Kinzinger have faced sharp blowback for joining Pelosi's committee, with conservatives arguing that they should be removed from their other committee slots. The two members have said those threats won't deter them.

"If the conference decided or if Kevin decides they want to punish Liz Cheney and I for getting to the bottom and telling the truth, I think that probably says more about them than it does for us," Kinzinger said Monday.

Congressional Republicans are planning their own programming to rebut the select committee, with McCarthy and the five members who the California Republican had planned to appoint to the committee holding a news conference Tuesday morning before the hearing. While the news conference will give them a venue to air their grievances, the Republicans won't be in the hearing room as a voice to defend Trump from the attacks he's likely to face from Democrats.

Instead, the two Republican voices on the select committee are the most vocal Trump critics in the House GOP conference.

Tuesday's hearing, however, is focusing more on the visceral danger the officers faced January 6 on the front lines at the Capitol.

Body-camera footage shows how Fanone was pulled into the crowd and tased repeatedly with his own stun gun. Gonell was beaten with a flagpole and his hand was sliced open. Dunn has spoken out about the racist attacks he and other Black officers faced that day. And Hodges was the officer in one of the most harrowing and well-known scenes from the riots, when he was writhing and screaming in pain while crushed in a doorway by a crowd of rioters.

"I want people to understand the significance of January 6. I want people to understand that, you know, thousands of rioters came to the Capitol hell-bent on violence and destruction and murder," Fanone previously told CNN.

This story and headline have been updated with additional developments Tuesday.