Young survivors of Wednesday's school shooting in Florida have announced a national march on Washington to demand political action on gun control.
Student organisers told US media that they were determined to make Wednesday's shooting a turning point in the national gun debate.
The attack, which left 17 students and staff members dead, was the deadliest US school shooting since 2012.
Yesterday protestors chanted "shame on you" to US lawmakers and the president.
Mr Trump said last year he would "never" infringe on the right to keep arms - a long-running and contested debate within the US.
In his first public comments on the gun control issue since the attack, Mr Trump blamed the Democrats for not passing legislation when they controlled Congress during the early years of Barack Obama's administration.
He also rebuked the FBI for missing signals before Wednesday's school shooting, after the organisation admitted it had failed to act on a tip-off about the suspected shooter Nikolas Cruz.
What are the students' plans?
Speaking on US television networks on Sunday morning, student survivors from Marjory Stoneman Douglas announced their March for Our Lives campaign.
They are planning to march on Washington on 24 March to demand that children and their families "become a priority" to US lawmakers. They want other protests to happen simultaneously in other cities on the same day.
"We are losing our lives while the adults are playing around," Cameron Kasky, a survivor from the school said.
It is one of many student-led protests amassing support on social media in the wake of Wednesday's attack.
On Saturday students and their parents - as well as politicians - took part in an emotionally-charged rally in Fort Lauderdale, close to Parkland.
Arguably the most memorable moment came when high school student Emma Gonzalez took to the podium and attacked the US president and other politicians for accepting political donations from the National Rifle Association (NRA), a powerful gun rights lobby group.
"If the president wants to come up to me and tell me to my face that it was a terrible tragedy and... how nothing is going to be done about it, I'm going to happily ask him how much money he received from the National Rifle Association," said Ms Gonzalez.
"It doesn't matter because I already know. Thirty million dollars," the 18-year-old said, referring to donations during Mr Trump's presidential campaign.
"To every politician who is taking donations from the NRA - shame on you!" said Ms Gonzalez, who took cover on the floor of her secondary school's auditorium during the attack.
According to the Center for Responsive Politics, the NRA spent $11.4m (£8.1m) supporting Mr Trump in the 2016 campaign, and $19.7m opposing Hillary Clinton.
What is Mr Trump's stance on gun control?
The president's views on gun control have shifted over time. In recent years, he has pledged to fiercely defend the Second Amendment to the US Constitution, which protects people's right to keep and bear arms.
In a tweet late on Saturday, the Republican president accused the Democrats of not acting on gun legislation "when they had both the House & Senate during the Obama Administration.
"Because they didn't want to, and now they just talk!" he wrote, referring to criticism from Democrats following Wednesday's shooting.
Mr Trump - who on Friday met survivors of the attack - has also blamed the shooter's mental health and the FBI's failings.
The US news network CNN has invited Florida lawmakers and the president to attend a town hall event with survivors of the attack on Wednesday.
Saturday's rally coincided with a gun show in Florida. Hundreds of people attended the event at the Dade County fairgrounds, despite calls to cancel it.
What do we know about the suspect?
Mr Cruz, 19, is a former student at the Marjory Stoneman Douglas High School.
He was reportedly investigated by local police and the Department of Children and Family Services in 2016 after posting evidence of self-harm on the Snapchat app, according to the latest US media reports.
Child services said he had planned to buy a gun, but authorities determined he was already receiving adequate support, the reports say.
The 5 January tip was not the only information the FBI received. In September, a Mississippi man reported to the law enforcement agency a disturbing comment left on a YouTube video under Mr Cruz's name.
Florida Governor Rick Scott called for FBI director Christopher Wray to resign over the failures to act.
In a late tweet on Saturday, the President rebuked the organisation for their handling of tip-offs.
"Very sad that the FBI missed all of the many signals sent out by the Florida school shooter. This is not acceptable. They are spending too much time trying to prove Russian collusion with the Trump campaign."