Most of the Parkland school shooting survivors were still a twinkle in their parents' eyes the day two gunmen shot and killed Coni Sanders’ father in a massacre at Columbine High School in 1999 – the largest school shooting in America at the time.

But less than 20 years later, on 14 February 2018, a gunman opened fire on Marjory Stoneman Douglas, killing 17 students and staff members in a shooting that officially pushed Columbine to fifth on the list of America’s deadliest school shootings.

“This has been 18 years of, every time there is a mass shooting all of the adults start screaming at each other and telling each other why they’re wrong,” said Ms Sanders, who has worked as a forensic therapist for violent offenders since her father, Columbine High School teacher Dave Sanders, was murdered.

“I think that this is kind of a wake-up call for people,” she said of the Parkland shooting, “because it’s the kids saying ‘enough is enough’.”

Indeed, since the day of the shooting, many students of Stoneman Douglas have spoken up unequivocally about the need for more gun control. They have staged rallies and walkouts, lobbied legislators, and even held a listening session with President Donald Trump.

Their passion has convinced some people that this will be the moment that changes history: the moment that Congress takes significant action on gun control, for the first time in more than 20 years.

“The amount of time that [the Parkland students] spend on social media and networking and problem solving is amazing,” Ms Sanders said. “And I know that that’s a complaint a lot of people have about younger generations, but this is what change looks like now.”

She added: “These kids are going to change the world.”

Florida shooting – in pictures Show all 10 1 /10 Florida shooting – in pictures Florida shooting – in pictures Police arrest a suspect in connection with the shooting at the Marjory Stoneman Douglas High School in Parkland, Florida Reuters Florida shooting – in pictures Parents wait for news after reports of a shooting at Marjory Stoneman Douglas High School in Parkland, Florida AP Florida shooting – in pictures Anxious family members wait for news of students AP Photo/Wilfredo Lee Florida shooting – in pictures Students being evacuated from the school AP Florida shooting – in pictures Students being evacuated from the school Getty Florida shooting – in pictures People gather waiting for word from students AP Florida shooting – in pictures Parents waiting for news on their children AP Florida shooting – in pictures People gather at a hotel where students were taken after the shooting Getty Florida shooting – in pictures Florida Governor Rick Scott speaks to the media as he visits Marjory Stoneman Douglas High School following the shooting AFP/Getty Florida shooting – in pictures Dr. Igor Nichiporenko, Medical Director Trauma, left, and Dr. Evan Boyer, Medical Director, Emergency Services, speak about treating victims and the suspect at a press conference outside Broward Health North hospital AP

Others, however, are less optimistic. Asked whether this massacre would be the one to spark change, Scarlett Lewis replied simply: “They said that about Sandy Hook too, and that was five years ago”.

Ms Lewis’s son, Jesse, was killed in the school shooting at Sandy Hook Elementary School in 2012. He was six years old.

Twenty-six students and teachers were killed that day when 20-year-old Adam Lanza opened fire on the Connecticut primary school. Many of the victims’ families rallied for stricter gun control laws after the shooting, and some even sued a gun manufacturer. Congress has introduced dozens of gun control bills in the years since, none of which have passed.

Veronique Pozner, who lost her son, Noah, in the shooting, shared Ms Lewis’s scepticism. She, too, thought more action would be taken in the wake of Sandy Hook.

“You’ve got little tiny children in first grade being slaughtered,” she said. ‘If that’s not an impetus for change, if that doesn’t propel the narrative forward, what possibly could?”

Florida shooting survivor asks Marco Rubio if he'll stop taking donations from the NRA

But at a major conservative political conference later that week, National Rifle Association (NRA) vice president Wayne LaPierre railed against efforts to expand gun control. The leader of the powerful, pro-gun lobbying group told a cheering crowd that gun control advocates were trying to “get rid of the second amendment” and “make all of you less free”.

At the same conference, Mr Trump told the audience: “There’s nobody who loves the second amendment more than I do and there’s nobody who respects the NRA [more].”

Jenny Hubbard, whose daughter, Catherine, died in the Sandy Hook shooting, says she has been avoiding coverage of this shooting. It was too painful, she said, to watch all of the parents pacing outside the school that day – Valentine’s Day – wondering whether their child had survived. It was the same place she had been in five years ago.

But Ms Hubbard has heard about the Parkland students: their walkouts, their marches, their speeches on gun control. Ms Hubbard doesn’t believe gun control alone will solve the problem of school shootings, but she appreciates the importance of the students speaking out.

“If having our youth teach us that they want to be heard is what makes us actually hear what they’re saying, then that’s a good thing,” she said.