Kimberly and Felix Rubio went twice to Robb Elementary school on the morning of 24 May, first to attend an end-of-year awards ceremony for their youngest son and then to attend one for their daughter, Lexi, who was in the fourth grade.

They beamed with pride as Lexi was honored with the “good citizen” award and recognized for earning straight As. To celebrate, they promised to take her for ice cream later that night.

“In the reel that keeps scrolling across my memories, she turns her head and smiles back at us to acknowledge my promise,” Kimberly Rubio told a House oversight committee via video link on Wednesday. “And then we left.”

Through tears she continued: “I left my daughter at that school and that decision will haunt me for the rest of my life.”

Felix Rubio sat silently next to his wife, eyes downcast as she described the harrowing events that followed: their desperate, hours-long search for their children. Relief when a teacher said their son was safe, and the moment they realized Lexi, their “intelligent, compassionate and athletic” daughter who dreamed of attending law school would not live to graduate the fourth grade.

“That opportunity was taken from her; she was taken from us,” her mother said.

Lexi Rubio was among the 19 students and two teachers killed when a gunman armed with an assault-style rifle stormed a pair of adjoining classrooms and opened fire. She was 10.

“We don’t want you to think of Lexi as just a number,” Kimberly Rubio said. “So today we stand for Lexi, and her voice demands action.”

The oversight committee hearing on gun violence was scheduled in the wake of successive mass shootings in recent weeks that have claimed the lives of dozens of Americans in Buffalo, New York; Uvalde, Texas, and elsewhere. The committee heard from a pediatrician, a police commissioner, the mayor of New York and experts on the issue of gun violence, who almost uniformly echoed the Rubios’ call for action.

But perhaps the most heart-rending testimony came from 11-year-old Miah Cerrillo, a fourth-grader at Robb elementary school. In a pre-taped video, Miah, wearing a shirt that said “live by the sun” with sunflowers, recounted how the gunman appeared in their classroom as they scrambled to hide behind desks and the rows of backpacks. He told her teacher “goodnight” before shooting her in the head, she said.

The gunman then shot her classmates and then her friend who was huddling next to her. “I thought he would come back to the room, so I grabbed blood and put it all over me,” she said.

Roy Guerrero, the sole pediatrician in Uvalde, said the horror of tending to the small bodies “pulverized” by bullets fired by an AR-15-style semi-automatic weapon, embedded memories he said “no prayer could ever relieve”.

Guerrero said he could save children from broken bones and bacterial infections, but only Congress could save them from the scourge of gun violence.

“Making sure that our children are safe from guns, that’s the job of politicians and leaders,” he said, adding: “We are bleeding out and you are not there.”

The Rubios pleaded with Congress to change gun laws and prevent more communities from experiencing the overwhelming tragedy that has consumed Uvalde, where Lexi’s classmates are still being buried.

Kimberly Rubio asked Congress to raise the age to 21 for purchases of military-style assault rifles, like the one that killed Lexi, as well as for strengthening background checks on gun buyers and repealing the immunity that shields gun manufacturers from being held liable.

As lawmakers chase an elusive deal on gun control, Kimberly Rubio urged a consensus: “At this moment, we ask for progress.”

Appearing on Capitol Hill, Miah’s father, Miguel Cerrillo, said something had to change. In brief, tearful testimony, he told the committee that the shooting had changed his daughter.

“I came because I could’ve lost my baby girl,” he said. “She’s not the same little girl that I used to play with and run with … because she was Daddy’s little girl.”

“I wish something would change,” he concluded, breaking down in tears. Congresswoman Rashida Talib led him out of the hearing room by hand.

The still-raw display of emotions underscored the depths of America’s gun violence crisis. But it also emphasized the gaping partisan divide that simmered and then flared on the floor of the House ahead of what was expected to be a party-line vote on a suite of gun reform measures.

“It is my hope that all my colleagues will listen with an open heart as gun violence survivors and loved ones recount one of the darkest days of their lives,” said congresswoman Carolyn Maloney, a Democrat of New York and the chair of the oversight committee. “This hearing is ultimately about saving lives, and I hope it will galvanize my colleagues on both sides of the aisle to pass legislation to do just that.”

The committee also heard from Zeneta Everhart, who recounted in graphic detail how close she came to losing her son, Zaire Goodman, who was shot in the neck during a racist mass shooting at the Tops Friendly supermarket in Buffalo where he worked. Thirteen people were shot in the assault, 10 fatally.

“Let me paint a picture for you: my son Zaire has a hole in the right side of his neck, two on his back and another on his left leg. Caused by an exploding bullet from an AR-15,” she said. “As I clean those wounds I can feel pieces of that bullet in his back.”

“I want you to picture that exact scenario for one of your children,” she said. “This should not be your story or mine.”

Everhart said it was naive to say, as so many do in the wake of senseless acts of violence, that the attacks do not represent “who we are as a nation”. Speaking as the descendant of enslaved Americans, she said the racist violence that erupted in a Buffalo supermarket last month had ugly roots in the nation’s founding.

“Hear me clearly,” she said. “This is exactly who we are.”

The committee also heard from Lucretia Hughes, a conservative activist invited to testify by Republicans. In fervent remarks to the committee, she said her son was killed in 2016 by a convicted felon who had illegally obtained a firearm. Gun control laws, which she described as “steeped in racism”, did little to save her son, she said.

“Y’all are delusional if you think it’s going to keep us safe,” Hughes said of the calls for new firearms restrictions. Citing the widely-criticized response by law enforcement officers in Uvalde, she added: “We must prepare to be our own first responders.”

But children and teachers shouldn’t have to bear that responsibility, Becky Pringle, president of the National Education Association, told the committee. The number of students who will never get to “live into their brilliance” is unconscionable, and yet it fails to capture the totality of the long-lasting physical and emotional damage wrought by these attacks, she said.

“Students across our country are writing goodbye notes and wills – just in case,” she exclaimed. “Unfortunately their fear is perfectly rational.”

In the video to the committee, Miah Cerrillo was asked if she feels safe at school.

Miah shook her head no.

“Why not?”

“Cause,” she said slowly, fidgeting as children often do, “I don’t want it to happen again.”

“You think it’s going to happen again?”

Miah nods her head. Yes, she thinks it will.

Kimberly Rubio also fears it will happen again. But she hopes, in honor of her daughter, that it can happen less, that, perhaps, with new laws and new restrictions, there will be fewer mothers in the future whose children go to school and never come home.

“Somewhere out there, there’s a mom listening to our testimony and thinking, ‘I can’t even imagine their pain,’ not knowing that our reality will one day be hers,” she said. “Unless we act now.”