Ridgefield, Connecticut (CNN) On the day of the massacre at Marjory Stoneman Douglas High School , Lane Murdock retreated to her bedroom in her parent's landmark home in this affluent Connecticut enclave that brims with the charm of small-town America.

The 253-year-old New England colonial sits behind a stone wall erected by a wary homeowner after the Lindbergh baby kidnapping in the early 1930s. But, as the Ridgefield High School sophomore sat in front of her laptop, with Benny Goodman playing on her portable turntable, it must have felt as though no fortification could ever protect a generation growing up in the age of the active shooter.

"That America's children are growing up in fear is something we're not talking about," said Lane, who recently turned 16. "No child should have to learn how to hide from a shooter."

That night, Lane came up with a plan for students to walk out of school in protest on Friday, April 20, the anniversary of the 1999 Columbine High School massacre.

"I thought, originally, it would just be my school but, obviously, it's grown," she said.

Indeed, more than 2,500 schools from New England to Hawaii were expected to participate, along with American students at Oxford and Cambridge universities in England and high schoolers in the US island territory of Guam.

Lane tweeted a photo of students at the walkout Friday afternoon.

"The work we have done today is beyond anything I thought I would ever see. There is so much more to come. I love you all! #NationalSchoolWalkout," she wrote.

The work we have done today is beyond anything I thought I would ever see. There is so much more to come. I love you all! #NationalSchoolWalkout pic.twitter.com/cRxfaR30DG — Lane Murdock (@lanemurdock2002) April 20, 2018

Students, many wearing orange , walked out of their classrooms at 10 a.m. local time to stand in remembrance of the young victims of mass shootings and demand real legislative solutions to gun violence.

Their actions became part of a burgeoning, student-led gun control movement born from an epidemic of campus attacks. It was expected to be the biggest walkout since March 14, when scores of students across the United States walked out of class to honor the Parkland victims and to make sure calls for change account for the broad context of gun violence.

"If you can't vote, you don't have a lot of concrete power," Lane said. "As a student, what do you have? What you have is your attendance in school, ... and there's power to that.

"Hey, if we can disrupt the national schedule of kids going to school and draw attention to this issue," she said, "then that's a step closer to change."

'We should be horrified, and we're not'

It wasn't so much the February 14 massacre at Stoneman Douglas but the absence in her community of any profound response to it that gave root to Lane's mission.

After a former student sprayed the Parkland, Florida, campus with a semiautomatic rifle , news alerts flashed on smartphones in Ridgefield, some 1,300 miles away. Then, everything just went back to normal.

"I remember I didn't have a huge reaction," Lane recalled. "And because of that, I needed to change myself, and we needed to change this country. We should be horrified, and we're not anymore."

As classes drew to a close that afternoon, the principal addressed students over an intercom. She talked about school safety and asked for a moment of silence for the Florida victims.

"Then she said, 'At the end of the day, it's up to you guys,'" said Lane, who took that to mean students -- rather than adults -- held responsibility for curbing the school shooting epidemic. "It kind of annoyed me. It was up to them to change this, and they haven't. That infuriated me."

So, Lane thought, "OK, if it's up to us, watch us."

As she wrote, Jimi Hendrix's stare from a poster on her wall gave her inspiration, Lane said.

"I'm very into symbolism," she said, "so I took that as a sign."

Lane and other Ridgefield students soon formed what would become the first chapter of the National School Walkout movement. In late March, she and others walked out of a school board meeting when it appeared officials would not support the walkout. The board relented.

Now, the group's Twitter account has 131,000 followers, and its sharp website offers a social media tool kit and other materials to help students join the cause.

More than 150 member chapters have formed around the country.

The movement, Lane said, is about "empowering students" to fight against federal and state government inaction on gun violence. It encourages young people to push for solutions that range from banning assault weapons to mandating universal background checks for gun buyers to allowing families to petition courts to remove guns from people at risk of hurting themselves or others, according to the walkout website

"It is not conservative or liberal," she said. "It's about making sure children don't get harmed in school and we don't live in a country that has institutionalized fear."

'This is the event of your life'

Lane and some of her classmates took to the streets March 24, for the national March for Our Lives demonstration in Washington, which was organized by young survivors-turned-activists from Parkland. Lane met some of them, along with teens who live with gun violence daily in cities such as Washington, Baltimore and Pittsburgh.

"There are kids ... who don't have the platform that I have, who haven't gotten the media attention they deserve," said Lane, whose mother is from Texas and father is from Puerto Rico. "I do come from a position of privilege, and I have the time and resources to do something like this."

Last week, on the warm, last day of spring break, her walkout chapter's members met at the Ridgefield rec center.

"I showed up a little late. I'm sorry," Lane told a small group of student leaders sitting behind Macs and notebooks.

"We understand. You're a celebrity," 17-year-old Paul Kim joked.

"And only a little over 16," teased Josh Burns, 16.

They discussed logistics: security for the walkout, tables for a voter registration drive and for writing letters to elected officials, food and water donations, the sound system, the guest speakers.

Lane Murdock, 16, discusses logistics with classmates a week ahead of Friday's National School Walkout.

"Student speakers, sometimes they're boring," said Paul, a senior. "Just off the top of my head, I can't really think of someone that I really want to see speak."

"That we don't have a lot of outside speakers is actually going to be a good thing," said Lane, who wears a small "I will vote" button. "It's about us."

Junior Grant Yaun, 17, called the walkout "a coming-of-age moment" for his generation.

Annie Colao, 18, said she wasn't "patting myself on the back" for being there during spring break but actually "feeling guilty for not having stepped up" against gun violence sooner.

"This fight does not stop after April 20," Lane said. "This is the event of your life. Be sure to communicate it that way."

'This is a lockdown drill'

The walkout has become a huge undertaking for Lane, who sometimes rises at 5 a.m. to respond to emails and phones calls. Then, she goes to class all day before juggling school work, event organizing and a couple media interviews in the evenings.

Lane's father, who works in telecommunications, helps his daughter with scheduling and fielding all the inquiries. He also drives her to appointments. But mostly, he said, he stays out of her business.

"She's always been her own person -- even since she was little," Paul Murdock said. "It's been all her."

Also long part of her life have been active shooter drills, which she recently lamented as a fixture since first grade.

"It's muscle memory for a lot of us," she said. "I can even recite it from memory: 'This is a lockdown drill. In the event of an actual emergency further instructions will be provided.' A teacher turns off the lights. Closes the door. Shut the blinds. ... It's built into us."

Lane was in fifth grade in 2012, when a young man shot and killed 26 people -- including 20 children -- at Sandy Hook Elementary School in Newtown, Connecticut, less than 20 miles away.

"I remember going home and seeing Mom crying," she said. "Sandy Hook was the first school shooting we can remember. Then, there were many more others."

Harking back to that tragedy, Lane said Friday's walkout is about ending the scourge of school shootings before another generation of American children grows numb to it all -- and about speaking for those whose lives it already has claimed.

"Of course, we're a generation that's passionate about gun control," she said. "We've lived this. A lot of the kids who attended Sandy Hook would be in high school now. We kind of symbolize these children who would have been our age."