Miah Cerrillo emotionally described smearing herself with her classmate's blood and playing dead as the Uvalde rampage unfolded, recounting the horror to the House Oversight Committee in a recorded video. Cerrillo was not in the room, as planned, when the video was played.
Cerillo said she and the other students hid behind the teacher's desk and their backpacks as the gunman shot out the window of their classroom and eventually entered.
WATCH: Miah Cerrillo shared her story on how she survived Uvalde school shooting
She said the gunman "told my teacher goodnight and shot her in the head, and then he shot some of my classmates and the whiteboard." Cerrillo then talked about putting the blood of a classmate on herself out of fear the gunman would return and using her teacher's phone to call 911.
Cerrillo said she didn't feel safe at school. When asked on the video if she thinks it will happen again, she shook her head yes.
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Her father told lawmakers Wednesday that he wishes something would change.
"She is not the same little girl I used to play and run with," he said.
Committee chair Rep. Carolyn Maloney, D-N.Y., opened the hearing by asking her colleagues to "listen with an open heart to the brave witnesses who have come forward to tell their stories about how gun violence has impacted their lives."
"Let us honor their courage," she said. "And let us find the same courage to pass commonsense laws to protect our children."
Maloney: “Gun violence is the leading cause of death for children in our country. As a society we are failing our children and we are failing each other. This out of control gun violence is a uniquely American tragedy…We stand alone in mass shootings." https://t.co/nfqudOlyAT pic.twitter.com/q5qoyj4qUu— ABC News Politics (@ABCPolitics) June 8, 2022
The committee also will hear from other families traumatized by the massacres in Uvalde and in Buffalo, New York, that killed a total of 31 people just 10 days apart.
Also testifying are Felix Rubio and Kimberly Rubio, the parents of Lexi Rubio, a 10-year-old girl killed in Uvalde; Zeneta Everhart, the mother of Buffalo shooting survivor Zaire Goodman, who was shot in the neck while working at the store; and Roy Guerrero, a Uvalde pediatrician who treated the victims.
WATCH: Zeneta Everhart testifies about son shot in Buffalo supermarket
Guerrero described in graphic detail treating the victims who arrived at Uvalde Memorial Hospital.
"Two children, whose bodies had been so pulverized by the bullets fired at them, decapitated, whose flesh had been so ripped apart, that the only clue as to their identities were the blood spattered cartoon clothes still clinging to them," he said. "Clinging for life and finding none."
WATCH: Uvalde pediatrician testifies on aftermath of Texas school shooting
A second panel appearing before the House committee Wednesday includes various officials and advocacy group leaders: Buffalo police commissioner Joseph Gramaglia; Greg Jackson, Jr., the executive director of the Community Justice Action Fund; Becky Pringle, president of the National Education Association; and Nick Suplina, senior vice president for law and policy at Everytown for Gun Safety.
Maloney spoke exclusively with ABC News Congressional Correspondent Rachel Scott ahead of Wednesday's hearing, telling her the survivors and families reached out to her committee and insisted on traveling to the nation's capital to share their experiences just mere weeks after witnessing horror -- hoping to change the hearts and minds of lawmakers on Capitol Hill.
"We were saying maybe it would be too difficult," she said, referring to Miah Cerrillo, of someone so young wanting to testify before Congress. "But she felt strongly and her parents supported her wish that she be able to testify and tell her story."
"She felt very, very strongly that her story -- she didn't want the loss of her teachers, the loss of her friends, but also the quick thinking that she had to play dead to smear blood all over herself to save her life. It's an incredible story," Maloney added.
The hearing comes as negotiations continue on gun control. A bipartisan group of lawmakers, led by Democratic Sen. Chris Murphy of Connecticut and Republican Sen. John Cornyn of Texas, are trying to reach a compromise this week on incremental measures like expanded background checks, incentives for states to implement red flag laws and funding for mental health programs.
Senate Democrats are looking for at least 10 Republican votes to get to the 60 needed to overcome a filibuster. If they don't reach that mark, they risk continuing a 30-year trend of inaction on gun reform even in the wake of such tragedies as Sandy Hook, Las Vegas and Parkland.
MORE: Uvalde teacher describes moment he saw shooter, trying to protect students
Murphy provided an update on the talks during an appearance on "The View" on Tuesday, stating he's never seen this much public pressure for elected officials to act and he's hopeful Republicans are "picking up this sense of urgency."
"While we are very different in our views, we do both agree that we are not willing to do anything that compromises people's Second Amendment rights," Murphy said. "We are focusing on keeping weapons out of the hands of dangerous people."
President Joe Biden made an impassioned plea last week for more, including a ban on assault weapons like the AR-15 used in the Uvalde shooting, but most Republicans in Congress remain opposed to any gun restrictions.
"We spent hours with hundreds of family members who were broken, whose lives will never be the same," Biden said in an address from the White House. "They had one message for all of us. Do something."
Maloney said she feels there is a new air of urgency to get gun control legislation on Biden's desk in light of the Uvalde mass shooting, and she's hopeful Republicans will change their minds when they hear the witnesses speak firsthand.
"Absolutely, there's a sense of urgency, and tomorrow we will be debating gun safety laws on the floor and voting. So, hopefully, their testimony will have an impact on the votes of these members of Congress," Maloney said Tuesday.
In a letter to Democrats, House Speaker Nancy Pelosi, D-Calif., said the House will vote Wednesday afternoon on the Protect Our Kids Act, the gun control package assembled after the mass shootings in New York and Texas.
In all, 19 young children and two teachers were killed by a gunman wielding an AR-15-style assault weapon at Robb Elementary School on May 24. Funerals for the victims are continuing until June 25.
In Buffalo, 10 Black people were fatally shot in a Tops grocery store on May 14. The Department of Justice is investigating the shooting as a "hate crime and an act of racially-motivated violent extremism."
On Tuesday, the Senate Judiciary Committee heard from the son of one of the Buffalo victims as part of a hearing on domestic terrorism.
Garnell Whitfield Jr., the oldest son of Ruth Whitfield, and 86-year-old woman killed in the shooting, held back tears as he urged lawmakers to take action or "yield their positions" in Congress.
"You expect us to continue to just forgive and forget over and over again. And what are you doing?" he said. "You're elected to protect us, to protect our way of life."
ABC News' Rachel Scott and Benjamin Siegel contributed to this report.