At Hamilton High School, the protest began with a young man and a bullhorn.
Ari Elkins, a senior, stood on the front lawn of his Palms school and in a voice both firm and loud, cried out: "No more silence! End gun violence!"
Seconds later, hundreds of his fellow students came pouring out the building's double doors.
Calm and defiant, they joined tens of thousands of students Wednesday in a historic national walkout, exactly one month after a gunman stormed a Parkland, Fla., school and killed 17 people.
All over the country, teenagers organized 17-minute protests, in honor of each of the victims. They wanted to show the effects of gun violence and push political leaders to take action to prevent future massacres on and off campuses.
In Parkland, at Marjory Stoneman Douglas High School, more than a thousand students first gathered first on the football field, and many then went on a spontaneous two-mile trek to a park where white crosses for each of the shooting victims form a makeshift memorial.
For many kids, the protest was not just a moment but the launch of a movement, the start of an era in which their generation — fueled by fear, anger and impatience — chooses to mobilize and demand the world's attention.
On March 24, thousands of young people are expected to participate in a separate event, March for Our Lives, organized by the survivors of the Parkland shooting. Many related protests are expected to happen on that day nationwide.
"Students are tired of waiting for their parents to do something about it," said Deshone Johnson, a 15-year-old sophomore at Hamilton. "Now this is our job."
In the weeks leading to the walkout, students took charge, with guidance provided by Empower, the youth arm of the Women's March organization. They used social media to spread their message with hashtags and videos. They made signs, banners and T-shirts and chose orange — worn by hunters with guns to protect themselves from one another — as their color of choice.
Students from close to 3,000 schools nationwide walked out — with or without official approval. Some persisted despite lockdowns and threats of suspensions and grade demotions.
In Washington, D.C., they sat silently for 17 minutes with their backs to the White House. In New York, they chanted and marched in the streets. In Sacramento, they arrived by the busload to protest the National Rifle Assn.
In Los Angeles, kids rose from their seats at 10 a.m. and spilled onto sidewalks, grassy fields, auditoriums and quads. They shouted from megaphones, recited poems and stood silent. Many also held voter registration drives.
At Granada Hills High School, students lined up to spell out #ENOUGH on their football field.
"Maybe if they see we're really serious about this, that we really can't stand this anymore, they will come to a change," said Evelyn Sanchez, 17, from Garfield High School.
Evelyn, a member of the student body government, was inspired to walk out of her classroom by the history of her own school.
Back in 1968, thousands from Garfield and other schools staged the Eastside "blowouts," walkouts that went on for more than a week demanding better learning conditions for Mexican American students.
As kids at Garfield left their classrooms Wednesday, they walked past posters honoring the 50th anniversary of the blowouts and headed to the school's field for an assembly. Orange paper hearts, each with the name of a Parkland shooting victim, adorned a chain-link fence.
Student leaders took turns at a microphone, speaking passionately.
One asked the audience: Raise your hand if you feel safe at school. Hardly any hands went up.
These days, many struggle not to be fearful when they hear a voice on the intercom.
For Deshone of Hamilton, Parkland was a pivotal moment. What happened there turned his fear into anger.
He's fighting for his 5-year-old sister who recently had an active shooter drill at her kindergarten. He prays she never has to experience the real thing.
"It's sad," he said. "She can't grasp the concept of life and death, and yet she has to [learn to] fight for it."
Students at Venice High School placed 17 desks out on the front lawn.
In single file, 14 students and three teachers approached the desks and placed flowers on them.
April Cuarenta of Watts spoke on behalf of Helena Ramsay, who died trying to protect a friend.
"Helena Ramsay," she said in a breaking voice. "I was 17."
"I was super emotional," April said afterward. "She was 17. I am 17. I want to tell her family that I understand how her life was ripped away."
Though most L.A. students stayed on school property, a large group from the Los Angeles Center for Enriched Studies, a Mid-City magnet, marched down busy La Cienega Boulevard. Cars honked in support. They were back in class by 11:20 a.m.
"Coming together with my peers, all fighting for something so simple that we can relate to … was a truly beautiful thing," said junior Lila Roan O'Connell.
Times staff writer Joy Resmovits and Times special correspondent Jenny Jarvie contributed to this report.
9:45 p.m.: This article was updated to add details of the walkout in Parkland, Fla.
6:10 p.m.: This article was updated to clarify details of the ceremony at Venice High School.