WATCH: Top Moments and Testimony From Thursday’s Jan. 6 Hearing

The House committee investigating the Jan. 6, 2021, riot called Donald Trump's behavior that day a "dereliction of duty" as it showed during a prime time hearing how the former president failed to halt the mob's attack on the Capitol.

One witness, former deputy press secretary Sarah Matthews, said Trump essentially gave the rioters "a green light" to continue with their violence as he said again, falsely, that the presidential election had been stolen.

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And in never-before-seen video, Trump can be heard refusing to say that the 2020 election was over.

The Thursday session was the committee's eighth public meeting. The hearings will continue in September.

"We have much work to do," Republican co-chair Rep. Liz Cheney of Wyoming said in conclusion.

Watch key moments from the hearing in videos:

As Rioters Invade Capitol, Trump Watches Fox News

The House committee investigating the Jan. 6, 2001, U.S. Capitol riot shared witness testimony on Thursday about then-President Donald Trump's failure to call for law enforcement intervention during the riot.

After the Secret Service refused to allow Trump to march to the Capitol with his supporters, he returned to the White House and watched the violence from a dining room off the Oval Office. It was turned to Fox News.

Witnesses said he made no calls to anyone who could have helped control the mob.

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'Fueling the Fire'

Matthew Pottinger, former deputy national security adviser, testified Thursday before the Jan. 6 committee that former President Donald Trump’s tweets during the U.S. Capitol riot enflamed tensions and escalated violence.

Rep. Elaine Luria, a Democrat from Virginia, said Trump had put a target on his vice president's back by tweeting: “Mike Pence didn’t have the courage to do what should have been done to protect our Country and our Constitution."

Witness Matthew Pottinger said that Trump was "fueling the fire" rather than trying to convince the rioters to go home.

Pence's Security Detail Say Their Goodbyes

A Secret Service official testified to the Jan. 6 committee that members of former Vice President Mike Pence’s detail feared for their lives during the attack on the U.S. Capitol.

Trump's attacks on Pence left the vice president's security detail worried enough about his safety that members made calls to their families to say goodbye, the committee heard.

"The members of the VP detail at this time were starting to fear for their own lives," an unidentified witness said."

GOP Sen. Josh Hawley Flees the Rioters

Sen. Josh Hawley, R-Missouri, was seen outside the Capitol before things escalated raising his fist to the crowd outside. The Jan. 6 committee showed footage of Hawley running through the hallways of the Capitol escaping the riots later that day.

Republican Sen. Josh Hawley of Missouri was seen raising his fist to the crowd outside the Capitol on Jan. 6.

But later that day, he appeared in another image: running through the hallways as the rioters invaded the building.

Luria said a law enforcement officer said she believed Hawley’s salute “riled up the crowd."

"It bothered her greatly," Luria said. "Because he was doing it in a safe space protected by the officers and the barriers."

Watch Trump in Never-Before-Seen Video

The Jan. 6 committee on Thursday showed outtakes from then-President Donald Trump's Jan. 7, 2021, speech, during which he repeatedly refused to say the election was over.

Trump, in never before seen video, refused to say in a statement the day after the riot that the 2020 presidential election was over. He would say only that Congress had certified the results.

"I don't want to say the election is over," he says in outtakes from his Jan. 7 videotaped statement.