Lori Alhadeff's 14-year-old daughter was shot and killed while at school in Florida.

Key points: Lori Alhadeff made a highly emotional plea to President Donald Trump

Lori Alhadeff made a highly emotional plea to President Donald Trump "Do something. Action. We need it now. These kids need safety now," she screamed

"Do something. Action. We need it now. These kids need safety now," she screamed Mr Trump has tweeted about the shooting, sending "prayers and condolences"

Alyssa Alhadeff was one of 17 people killed at Marjory Stoneman Douglas High School by suspected shooter Nikolas Cruz.

On Friday, after making arrangements for her child's funeral, Ms Alhadeff made a highly emotional plea to President Donald Trump.

The gunman, a crazy person, just walks right into the school, knocks down the window of my child's door and starts shooting, shooting her, and killing her.

"President Trump, you say 'what can you do', you can stop the guns from getting into these children's hands.

"What can you do? You can do a lot.

"This is not fair to our families that our children go to school and have to get killed."

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In a very raw appearance on CNN, Ms Alhadeff shouted into the camera.

Fighting tears, her voice quaking with anger, she screamed: "Do something. Action. We need it now. These kids need safety now."

Mr Trump has tweeted about the shooting, sending "prayers and condolences".

He also addressed the shooting in a White House speech that focussed on school safety and mental health but made no mention of gun policy.

Gun control in America is a very divisive issue, but the pleas from Florida are for US leaders to start looking past their politics.

Ms Alhadeff's comments came as a student who was inside a classroom throughout most the massacre made a similar plea to political leaders.

And his straight-talking message is being heard around the world.

Teen begs politicians for change: 'you guys are the adults'

David Hogg is a senior student at Marjory Stoneman Douglas High School.

Sorry, this video has expired David Hogg initially tried to evacuate, but then realised 'this was not a drill'

A day after the shooting, the 17-year-old has been on several major news channels with some powerful calls to action.

Mr Hogg is pleading with US politicians to make gun control less about "ideas that help you get re-elected" and more about "action that results in saving thousands of children's lives".

He told CNN:

"My message to lawmakers in Congress is please take action. Ideas are great. Ideas are wonderful and they help you get re-elected and everything. But what's more important is actual action.

Children will continue to die if we don't take a stand now.

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What action does he want them to take?

Anything that is about policy, not politics.

"Any action, at this point, instead of complete stagnancy and blaming the other side of the political aisle would be a step in the right direction," Mr Hogg said.

"Working together to save these children's lives is what this country needs."

This line has resonated around the world:

"Please, this is the 18th one this year. That's unacceptable. We're children. You guys are the adults. You need to take some action and play a role. Work together. Come over your politics and get something done."

Sorry, this video has expired David Hogg says 'this is not acceptable'

The United States has been here before

This was the worst high school shooting in American history, but in 2012 at Sandy Hook Elementary School, 20 children in grade 1 were shot and killed. Six adults were also killed.

The AR 15 rifle allegedly used by Mr Cruz in Thursday's shooting was purchased legally at a store called Sunrise Tactical Gear in Florida.

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So what action can be taken now?

In Mr Trump's address, he didn't mention gun control, but he did mention mental health.

He said he planned to travel to Florida meet with victims' families, explore how to better secure schools and to "tackle the difficult issue of mental health".

US Attorney General Jeff Sessions said he wanted the Justice Department to study how mental illness affected criminal behaviour, to better understand how law enforcement could use existing laws to prevent school shootings.

Mr Sessions told a group of sheriffs in Washington:

It cannot be denied that something dangerous and unhealthy is happening in our country.

"[In] every one of these cases, we've had advance indications, and perhaps we haven't been effective enough in intervening."

Republican Governor Rick Scott said he had already told Florida House Speaker Richard Corcoran that "if someone is mentally ill, he should not have access to a gun".

Broward County Sheriff Scott Israel called for giving law enforcement more power to detain people who make "graphic threats or post disturbing material online".

He would like the authority to bring them involuntarily to mental health professionals to be examined.

Broward County Schools Superintendent Rob Runcie said: "now is the time to have a real conversation about gun control legislation."

And if adults cannot manage that in their lifetimes, he said, students will do it.

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ABC/wires