Just days before the 10th anniversary of the Newtown, Connecticut, school shooting, and six months after a similar massacre in Uvalde, Texas, President Joe Biden and House Speaker Nancy Pelosi gathered Wednesday night with families of some of the victims at the 10th annual National Vigil for All Victims of Gun Violence.
"I know that feeling," Biden, whose own son died of cancer, said of the grieving process. "It's like a black hole in the middle of your chest that you're being dragged into and you don't know if there's ever a way out."
Pelosi also addressed the gathering, taking aim at legislators who stand against gun reform.
"As we say to our colleagues, your political survival is nothing compared to the survival of our children," Pelosi said. "How can you not see that and take the hard vote?"
Among those gathered were families from Uvalde, where 19 students and two of their teachers were killed during a shooting at Robb Elementary School on May 24.
They descended on Washington, D.C., this week to renew their push for additional gun safety legislation, including a proposed ban on assault weapons that is heading for debate in the Senate.
"We are trying to put pressure on the Senate to put the bill to the floor to vote even if it's just for accountability," Kimberly Rubio, whose daughter Lexi was killed in Uvalde, told ABC News Tuesday at a silent protest on Capitol grounds. "We want to see where senators stand so their constituents can take that into consideration."
H.R. 1808, which would ban assault-style weapons for civilians, passed in the House of Representatives in July, only weeks after the Uvalde massacre.
Rubio has been vocal in her support for gun reform, including a proposal to raise the minimum age to purchase a rifle to 21. She addressed the crowd at the Wednesday night vigil after Biden.
"I feel numb most days. I'm operating on fumes," Rubio told the mourners.
"This is my reality. Speaking here because my 10-year-old daughter was murdered in her classroom," she said. "If not my child, whose? If not now, when? Lexi was the light of our lives and that is obviously now in the darkness."
Uvalde:365 is a continuing ABC News series reported from Uvalde and focused on the Texas community and how it forges on in the shadow of tragedy.
Jazmin Cazares, 17, whose sister Jacklyn Cazares was killed at Robb Elementary, told the vigil: "There's so much more to be done."
"Today we're here to remember Jackie, her classmates, her teachers and to remember every single person whose lives were cut short due to senseless gun violence," Jazmin Cazares said.
St. Mark's Episcopal Church by Capitol Hill was filled with many of the nation's leading gun reform activists, including the Newtown Action Alliance, and survivors from the Sandy Hook Elementary School shooting, which occurred on Dec. 14, 2012.
Jackie Hagerty, who survived Sandy Hook, said, "We are asked to be brave as we had under our desks while too many elected officials lack the courage to pass common sense gun laws."
The Bipartisan Safer Communities Act, which also passed one month after the Uvalde shooting, was the first gun reform signed into law in 28 years. But activists are demanding more.
Po Murray, co-founder and chairwoman of Newtown Action Alliance, introduced the president and Pelosi on Wednesday night, saying, "More than 400,000 Americans have been killed by guns in every corner of our country... Gun violence is a public health emergency."
Incoming Democratic Rep. Maxwell Frost of Florida, the first member of Gen Z elected to Congress, said gun violence is a defining characteristic of the lives of America's youth.
"We are the generation of mass shootings. It feels like in high school I went through more school shooting drills than fire drills," Frost told the crowd. "This is the reality for students in America."
At the vigil, Biden called it "commonsense" to ban assault weapons, limit the number of bullets allowed in a cartridge and restrict the types of weapons that can be bought and sold.
He said that the federal government had banned assault weapons before. "We can do it again," he said.
Biden praised the attendees for turning "pain into purpose."
"Scripture says, 'The light shines in darkness, and the darkness has not overcome it,'" Biden said. "All of you here tonight, you are the light. You are literally the light. And your loved ones, and your friends, they're the light."
"How many of you ask yourself, 'What would my son or daughter want me to do at this moment?'" Biden said. "They're in your heart, they're part of you, they're always going to be with you."
"We ask God," he said, "give us the strength to finish the work left undone, and on behalf of the lives we've lost and all the lives we can save."
The vigil, organized by the Newtown Action Alliance, was held one week before the 10-year anniversary of the Sandy Hook school shooting, when a gunman armed with a semi-automatic rifle killed 20 first-graders and six adults.
Earlier this year, Congress passed the most comprehensive federal gun safety law in decades.
The Bipartisan Safer Communities Act -- crafted in the wake of the devastating mass shootings in Buffalo, New York and Uvalde, Texas -- includes funding for mental health services and community safety programs.
It also closed the so-called "boyfriend loophole" to prevent convicted domestic abusers from purchasing a firearm for five years, and enhanced background checks for gun buyers age 21 and younger.
Biden celebrated the legislation as a "monumental" achievement but said there was more work to do to confront the tidal wave of gun violence across the country.
Biden has pushed for a ban on assault weapons, universal background checks and raising the minimum age to purchase guns from 18 to 21.
After five people were killed at an LGBTQ nightclub in Colorado Springs last month, Biden again called to get "weapons of war off our streets."
ABC News' Ben Gittleson contributed to this report.