Naomi Wadley, an 11-year-old from Alexandria, Virginia, told the rally she led a walkout at her school to remember a schoolgirl in Alabama, Courtlin Arrington.

She received a huge cheer when she said she represented all African-American women who are forgotten in this debate.

Zion Kelly addressed the crowds now in Washington.

"Just like you, I've had enough," he told them.

The Washington teenager lost his brother Zaire to an armed gunman last year. Four months later, a pupil at his school was shot dead.

He told the Washington Post earlier this week that he felt frustrated inner-city victims were not given the same attention as those in Florida.

Image source, AFP

In Los Angeles, student Edna Chavez told the crowd: “I have lived in south LA my entire life and have lost many loved ones to gun violence.

“This is normal, normal to the point that I have learned to duck from bullets before I have learned how to read.”

The former president, who once confessed to the BBC that US gun laws were "the greatest frustration of my presidency", tweeted his support for Saturday's marches.

Mr Obama and his wife, Michelle Obama, penned a letter to the student activists earlier this week.

"Throughout our history, young people like you have led the way in making America better,” they wrote.

“There may be setbacks; you may sometimes feel like progress is too slow in coming. But we have no doubt you are going to make an enormous difference in the days and years to come, and we will be there for you.”

The Marjory Stoneman Douglas High School survivors have just delivered impassioned speeches at the DC rally.

Delaney Tarr said: "We will continue to fight for our lives. We will continue to fight for our dead friends. There will be no faltering, no pauses in our cause.

"There must be more requirement for a person to access a gun than just a wad of cash."

David Hogg said: "If you listen real close, you can hear the people in power shaking. When politicians say that our voices don’t matter because the NRA owns them, we say: 'No more!'"

"When politicians send their thoughts and prayers without taking action we say: 'No more!'"

Alex Wind said: "People believe that the youth of this country are insignificant. People believe that the youth have no voice.

"When Joan of Arc fought back English forces she was 17 years old! When Mozart wrote his first symphony he was eight years old!"

Organisers said there would be hundreds of rallies across the US. The largest is in Washington but here's a flavour of what else is happening.

Image source, Getty Images

Image source, Reuters

Image source, Getty Images

Image source, Getty Images

Image source, Reuters

Celebrities have been eager to sprinkle their stardust on this movement.

George and Amal Clooney, late-night show host Jimmy Fallon and singer Cher are planning to be at the DC march.

The Clooneys praised survivors of the Parkland shooting in a letter published in the Guardian on Friday.

It said: "Amal and I stand behind you, in support of you, in gratitude to you. You make me proud of my country again."

Kim Kardashian and Kanye West have also flown into DC to join the demonstration.

Lin-Manuel Miranda, Miley Cyrus, Ariana Grande, Jennifer Hudson, and Demi Lovato were among the DC musical performers.

Beatles legend Sir Paul McCartney was at the march in New York, Manhattan. He told CNN he had a personal stake in the gun control debate.

"One of my best friends was shot not far from here," he said, referring to Beatles bandmate John Lennon, who was gunned down near the park in 1980.

Image source, Getty Images

Actresses Amy Schumer, Skai Jackson, Connie Britton and Olivia Wilde are among speakers at the Los Angeles march.

Horror author Stephen King, TV host Ellen DeGeneres and singers Taylor Swift, Justin Timberlake and Garth Brooks are among other celebrities who have tweeted support for the marchers.

Mass school shootings typically reignite the US gun control debate until the topic gradually fizzles out. That paradigm changed after Parkland, Florida. Here's why.

Image source, Getty Images

A key component of the student-led campaign is highlighting change through the power of voting.

March For Our Lives activists want US lawmakers who are up for re-election this year to ban the sale of assault weapons and tighten background checks for all gun buyers.

Organisers provided a link on their website for teenagers to register to vote while HeadCount, which runs voter registration drives at live music events, partnered with the march to deploy as many as 1,000 volunteers in Washington on Saturday.

"Our main message is we are not going to be quiet, we will keep fighting. I don't care how much money you have, your money can't drown out the sounds of our voices," 17-year-old Lauren Tilley told the AFP.

"We will be voting in 2020. Our generation wants change."

Connecticut's Democratic Senator Chris Murphy, a vocal gun control activist, told the news agency the movement needs to become an "electoral force, and this march may be the beginning of that".

As legislatures across the US debate how to prevent school shootings, one educational authority in Schuylkill County, Pennsylvania, believes it has hit upon a solution.

Blue Mountain School District has been putting a five-gallon bucket of rocks in each classroom for students to pelt at any would-be attacker.

"We, as a district, feel like that is a better alternative than sitting and crawling under a desk waiting to be shot," said Superintendent Dr David Helsel.

Whether anyone would be brave enough to take on a gunman using such a primitive weapon, exposing his or her vital organs in the process, remains to be seen.

Here’s Dr Helsel explaining the policy:

The BBC spoke to young people at the Conservative Political Action Conference recently in Washington, to get their take on the #NeverAgain movement.

Although they disagreed with the aims of the Parkland students, they supported their rights to protest and admired their energy.

“I don’t agree with them but I think it’s awesome that they are able to do what they’re doing” said one girl.

Watch the video in full

Families of a school shooting that happened in the UK in 1996 have joined a demonstration at the US consulate in Edinburgh.

Sixteen primary school children and one teacher were killed by a gunman in the Scottish town of Dunblane, in the deadliest such atrocity ever committed in Britain. Wimbledon champ Sir Andy Murray was among the survivors.

It sparked a national debate about firearms laws and paved the way for a handgun ban.

In London on Saturday, several hundred people including American actor Josh Gad gathered outside the new US embassy in Vauxhall.

Image source, PA

Marjory Stoneman Douglas high school students have travelled to the US capital to make their voices heard.

But crowds of supporters are carrying on their message back home in Parkland, Florida.

Image source, Reuters

Fox News host Tucker Carlson said on his Friday night show that a couple of student activists from Marjory Stoneman Douglas High School in Parkland, Florida, were extremists.

He singled out David Hogg and Emma Gonzalez, two of the most outspoken survivors from last month’s mass shooting, accusing them of ignoring the opinions of gun-rights adherents.

"If you honestly don't care what the people who disagree with you think, if you believe they want to, quote, murder more children, then who are you?

"Well you're angry, you're definitely not fit to be making policy for the rest of us. You are by definition an extremist.

"You should not have power if you really believe anyone who disagrees with you is evil and wants to kill the innocent."

While he supported Hogg and Gonzalez's right to express their opinions, Carlson argued they were too traumatised by February's massacre to partake in the debate.

The presenter said of Hogg: "He is a kid. He has just been through unspeakable tragedy. And that's why adults shouldn't be using him or his friends to push their agendas to the rest of us."

The BBC's Marianna Brady is at the march in Washington, DC, where she spoke to a student who lost her boyfriend in the Parkland shooting.

Image source, Getty Images

"He was my soulmate,” said Victoria Gonzalez, looking down at a sign of her boyfriend Joaquin Oliver.

Valentine’s Day -14 February- started off as a great day for Victoria.

“Joaquin and I exchanged gifts in the morning and he walked me to class. I was so happy.”

Later that day Victoria would learn that Joaquin was one of 17 people shot and killed on the other side of Marjory Stoneman Douglas school.

“It wasn’t real. It’s taken awhile for it to sink in. I’m here today so no one ever has to face this again,” she said, standing in a crowd of several thousand in Washington, DC at the March for Our Lives rally.

The crowds started to gather in the early hours of the morning outside the US Capitol.

Chants for “no more NRA” and “no more guns” erupt every few minutes at random.

“It gives me a lot of hope seeing how many people are out here supporting us. It feels like the whole entire world is on our side,” Victoria said.

Teenagers affected by gun violence will headline the speakers on stage at the rally in Washington from noon local time (1600 GMT).

In addition, there will be musical performances by Miley Cyrus, Ariana Grande, Jennifer Hudson, Demi Lovato, Lin-Manuel Miranda and Ben Platt.

Twenty-two people were killed in a suicide bombing at Grande's concert in the UK last year.

Miranda and Platt, stars of hit musicals Hamilton and Dear Evan Hansen, will perform their charity duet.

President Trump, who is at his Florida golf club Mar-a-Lago this weekend, is known to keep abreast of cable news, so he is no doubt across media coverage of today's marches.

The White House has issued a statement praising the protesters. It also touted three incremental steps it took on Friday to make American public spaces safer. Two such measures were inserted into a sweeping $1.3tn spending bill signed by the president.

• US law already bans those convicted of certain crimes from possessing a firearm, but spotty data has allowed dangerous felons to slip through gaps in the system and buy a gun anyway. On Friday, Trump signed the FIX NCIS Act, which aims to patch up the holes in the National Instant Criminal Background Check System. The bipartisan measure was backed by the National Rifle Association.

• Trump also enacted the STOP School Violence Act, which diverts money from an existing federal school safety grant programme towards funding security measures such as metal detectors.

• The Trump administration also announced it would ban bump stocks, devices that allow semi-automatic rifles to fire like machine guns.

Here's today's White House statement:

"We applaud the many courageous young Americans exercising their First Amendment rights today. Keeping our children safe is a top priority of the President’s, which is why he urged Congress to pass the Fix NCIS and STOP School Violence Act, and signed them into law. Additionally, on Friday, the Department of Justice issued the rule to ban bump stocks following through on the President’s commitment to ban devices that turn legal weapons into illegal machine guns."

Image source, Reuters

Gun rights are a hugely divisive issue in the US.

So what is the basis for the right to bear arms? And what key events have helped shape the debate?

It all started with 27 words.

Four key dates in the US gun debate

Image source, Getty Images

Students from Marjory Stoneman Douglas High School in Parkland, where 17 people were killed in February, are leading the worldwide rally for change.

Some of them explain below why they're in the US capital city today.

The BBC also spoke to them as they arrived in Washington on Thursday night.