Santiago Mayer, executive director of Voters of Tomorrow, shed light on Generation Z's perspective at the Los Angeles rally.

"We have grown up in a world where we all jump when a balloon pops. In a world where we have to scan every single exit and the movements of our classmates at school," he said.

"We don't live like this because we like it … we live like this because every single day the people in power make the conscious decision to put the NRA's money over our lives," Mayer said. "It's incredibly frustrating to keep talking about this, because every time that we try and do something, the other side just throws their hands up in the air and gives us 'thoughts and prayers.'"

Meyer said that "Generation Z is done with the games, done with the 'thoughts and prayers.'"

"We must take action now," he said. "We must ban assault rifles and high-capacity magazines. We must invest in school counselors and social services. We must raise the minimum age to buy a gun to 21."

Lawmakers, he said, "can vote for common sense gun legislation, or young people will vote them out."

At the March For Our Lives rally in Los Angeles, one woman held a sign reading: "Send the guns to Ukraine."

Dr. Jeffrey Birnbaum, a pediatric emergency medicine doctor in LA and a Parkland, Florida, native, explained the severity of semi-automatic rifle injuries.

He recalled his first experience treating patients shot by semi-automatic rifles, saying "the images of their injuries will be forever burned into my mind."

"I vividly remember thinking that no one should be able to inflict these types of injuries on a fellow human being," Birnbaum told the crowd.

A survivor of the 2014 mass shooting at the University of California Santa Barbara also shared her experience at the LA rally. She said after the shooting, her mother begged her to drop out of college, terrified for her safety.

Last month's Uvalde, Texas, shooting came one day after the anniversary of the UCSB massacre. She said she doesn't want any other generation to endure this grief.

"I know that we are exhausted -- but we must continue showing up … because I can't take it anymore," she said.

Buffalo, New York, residents held a March For Our Lives rally on Saturday, weeks after a mass shooting that killed 10 shook their community.

Another rally was in Parkland, Florida, home to the 2018 school shooting that killed 17.

Americans in cities across the nation, from New York to Chicago, also joined in, taking to the streets and making their voices heard.

"We need fewer guns in schools -- not more of them!" Randi Weinstein, president of the American Federation of Teachers, said in a passionate speech in Washington, D.C.

"Teachers want to be teaching!" she said. "As we head back to school this fall, please arm us with resources -- with books, with school counselors. Not with bulletproof vests."

Weinstein also addressed critical race theory, noting, "If we have the judgment to shoot a bad guy, why don't we have the judgment to plan our lessons?"

Manuel Oliver, whose son, 17-year-old, Joaquin was killed in Parkland, said in Washington, D.C., "Our elected officials betrayed us and have avoided the responsibility to end gun violence."

He said, "If lawmakers who have the power to keep us safe from gun violence are going to avoid taking action," then he's calling for a nationwide strike of schools, from elementary to college.

"Avoid attending school if your leaders fail … to keep us safe," he said. "Avoid going back to school if President Biden fails to open a White House Office of Gun Violence Prevention so that we can finally give this issue the attention that it deserves."

Oliver appeared on stage with David Hogg, a Parkland survivor and March For Our Lives co-founder, who vowed, "This time is different."

"This is not a political issue -- this is a moral issue," Hogg said.

He suggested combatting gun violence the way the U.S. addressed cigarettes.

"With cigarettes, we didn’t just change the laws -- we addressed why people want to smoke in the first place," Hogg said. "We have to address how people get guns and why they feel the need to pick them up in the first place. We must address the fact that the reason why communities like Parkland don't have shootings on a daily basis isn't because we necessarily have the strongest laws … we have some of the most resources."