(CNN) To those who say it's too soon after the school massacre to talk about politics and gun control, the students of Marjory Stoneman Douglas High see your point.

"We can respect that. We've lost people. It's important to mourn," junior Cameron Kasky said Sunday.

"Here's a time to talk about gun control: March 24. My message for the people in office is: You're either with us or against us. We are losing our lives while the adults are playing around."

Be forewarned: They're coming for the National Rifle Association and any politician who takes money from the gun lobbyist, Kasky and his classmates said. The NRA did not immediately return CNN's call seeking comment.

Kasky and his fellow students hope their efforts will dovetail with other events, national and local, aimed at persuading leaders to take meaningful action to keep schools safe.

They include two school walkouts , as well as a trip this week to Tallahassee, during which several Parkland youngsters hope to have sit-downs with legislators in the state Capitol.

According to a mission statement for March For Our Lives , students across the country will converge on Washington next month to say the nation can no longer wait to tackle issues of school safety and gun control reform. They're asking that like-minded folks who can't make it to the nation's capital stage solidarity marches in their own communities.

"Every kid in this country now goes to school wondering if this day might be their last. We live in fear," the March For Our Lives website says. "It doesn't have to be this way. Change is coming. And it starts now, inspired by and led by the kids who are our hope for the future. Their young voices will be heard."

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Kasky thanked the older generation that provided him and his contemporaries with "endless support." But, he flatly told them, in light of the Parkland, Florida, school shooting that left 17 of his teachers and classmates dead and what he sees as continued inaction from adults, "We don't need you."

"You are going to be seeing students in every single major city marching and we have our lives on the line here, and at the end of the day, that is going to be what's bringing us to victory and to making some sort of right out of this tragedy," he said. "This is about us begging for our lives."

'Badge of shame'

Kasky appeared on CNN with four fellow students, including Emma Gonzalez and David Hogg, who have been outspoken since Wednesday's shooting about the need to reform gun control laws.

"We've sat around too long being inactive in our political climate, and as a result, children have died," Hogg said. "If our elected officials are not willing to stand up and say, 'I'm not going to continue to take money from the NRA because children are dying,' they shouldn't be in office and they won't be in office because this is a midterm year and this is the change that we need."

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Kasky went so far as to say he and his classmates wanted to stigmatize politicians who take campaign contributions from the NRA.

"This isn't about the GOP. This isn't about the Democrats," he said. "This is about us creating a badge of shame for any politicians who are accepting money from the NRA and using us as collateral."

Gonzalez added, "We are going to be the difference." At a Saturday rally, the senior told a crowd of hundreds that the time for inaction was over.

"Maybe the adults have got used to saying, 'It is what it is,'" Gonzalez said in a fiery speech . "But if us students have learned anything, it's that if you don't study, you will fail. And in this case if you actively do nothing, people continually end up dead."

"We are going to be the kids you read about in textbooks. Not because we're going to be another statistic about mass shooting in America, but because, just as David said, we are going to be the last mass shooting," she added.

Florida lawmakers will experience the Parkland students' political motivation firsthand when they arrive at the state Capitol on Wednesday to speak to members of the Legislature.

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Ryan Deitsch, 18, a senior planning to make the six-hour trip, says organizers have arranged buses to transport about 100 people, students and chaperones, to the capital. They'll travel Tuesday night and plan to address senators Wednesday morning and representatives that afternoon. The plan is to split up into teams of three to five students and visit with legislators individually, he said.

Deitsch concedes that while the students are educated, they're still high schoolers, so listening to the legislators will be an important component of the meetings. The students don't have all the answers, he said, so it's important for them to understand what lawmakers feel is actually feasible, in terms of solutions.

"We just know anything is a better solution than nothing," he said. "There are way too many people who have died, and if they keep dying, they're dying for no reason."

Missed signs

Details of what may have been warning signs missed by authorities, school officials and those who were in contact with shooter Nikolas Cruz continue emerging in the aftermath of the shooting.

The FBI failed to act on a January 5 tip of information about "Cruz's gun ownership, desire to kill people, erratic behavior and disturbing social media posts, as well as the potential of him conducting a school shooting," the agency said.

The proper protocols weren't followed and the FBI's Miami office was not notified, the agency said.

Photos: Deadly Florida school shooting Parents wait for news after a shooting at Marjory Stoneman Douglas High School in Parkland, Florida, on Wednesday, February 14. At least 17 people were killed at the school, Broward County Sheriff Scott Israel said. The suspect, 19-year-old former student Nikolas Cruz, is in custody, the sheriff said. The sheriff said Cruz had been expelled for unspecified disciplinary reasons. Hide Caption 1 of 13 Photos: Deadly Florida school shooting Police officers ride in the back of a pickup truck as they tend to a victim. Hide Caption 2 of 13 Photos: Deadly Florida school shooting People are brought out of the Marjory Stoneman Douglas High School after the shooting. Hide Caption 3 of 13 Photos: Deadly Florida school shooting Police officers surveil the exterior of the school while the shooting was active. Hide Caption 4 of 13 Photos: Deadly Florida school shooting Students and faculty are evacuated from the school. Hide Caption 5 of 13 Photos: Deadly Florida school shooting A father and daughter embrace after a mass shooting at the Marjory Stoneman Douglas High School. Hide Caption 6 of 13 Photos: Deadly Florida school shooting Family members wait for word from students beneath an underpass just south of the campus of Marjory Stoneman Douglas High School. Hide Caption 7 of 13 Photos: Deadly Florida school shooting Lavinia Zapata embraces her son, Jorge, after he was evacuated from the school. Hide Caption 8 of 13 Photos: Deadly Florida school shooting The suspect, 19-year-old former student Nikolas Cruz, is taken into custody by authorities. Cruz was apprehended off of the campus. Hide Caption 9 of 13 Photos: Deadly Florida school shooting Security instructs parents following the shooting. Parents were told they would be reunited with their children at a local Marriott Hotel. Hide Caption 10 of 13 Photos: Deadly Florida school shooting Students released from lockdown console each other. While some students were evacuated, many remained in the school until authorities could come to their aid. Hide Caption 11 of 13 Photos: Deadly Florida school shooting Family members embrace after shooting. Hide Caption 12 of 13 Photos: Deadly Florida school shooting People embrace while leaving the Fort Lauderdale Marriott Coral Springs Hotel, which authorities designated as a staging point for witnesses to the shooting. Hide Caption 13 of 13

A video blogger said he warned the FBI in September about a possible school shooting threat from a YouTube user with the same name as Cruz. The FBI did not find information to identify the person who posted the comment and no connection was made to South Florida, said Robert Lasky, FBI special agent in charge of the Miami division.

Attorney General Jeff Sessions ordered a review Friday into how the Cruz tip was missed and how authorities respond to similar situations.

Cruz's school disciplinary record shows he was reprimanded many times since middle school for incidents that included bad language and disrupting class. He was also punished once for fighting and once for assault.

Laurel Holland, a retired teacher who had Cruz in her English class during his junior year, said Cruz cursed her out during midterm exams and was suspended for two days in 2016.

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There was a time when Cruz was caught at school with a gun-related object in his backpack, but Holland said teachers don't know what to do when kids exhibit "nebulous" behavior.

Kids who act out are referred to administrators, she said. Kids who cut class get detention. If she saw someone with suspicious bruises, she'd know to call social workers, who would get police involved. But with Cruz, there was no clear path.

"He fell through the cracks because we don't know what to do," she said.

The gunman's future

Cruz, who is facing charges of premeditated murder, is willing to plead guilty to avoid the death penalty, according to the public defender's office representing him.

There's no question Cruz killed 17 students and staff members in Wednesday's shooting at the high school in Parkland, Broward County public defender Howard Finkelstein said.

"The only question is, does he live or does he die?" Finkelstein asked.

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State Attorney Michael J. Satz said Saturday that this "certainly is the type of case the death penalty was designed for," but now is the time "to let the families grieve and bury their children and loved ones."

The 19-year-old is being held without bond in Broward County.

Cruz's digital footprint includes slurs against blacks and Muslims, and declarations of a desire to shoot people. Other social media posts show a photo of a rifle, a collection of firearms on a bed and a photo taken through a scope looking out a window.

In a private Instagram group chat, Cruz talked about killing Mexicans, keeping black people in chains and cutting their necks. After one member expressed hatred for gay people, Cruz concurred, saying, "Shoot them in the back of head."

As of Sunday, four patients injured in the shooting remained hospitalized in fair condition, according to Broward Health. On Saturday, Broward Health Systems mistakenly told CNN only three people remained hospitalized.

It is not clear when students will return to Marjory Stoneman Douglas. The school is closed through Wednesday, and officials say they hope to reopen the doors by week's end.