CNN will hold a town hall with the victims' classmates, parents and community members. "Stand Up: The Students of Stoneman Douglas Demand Action" will air live Wednesday at 9 p.m. ET.

(CNN) In an emotional rally Saturday in Fort Lauderdale, politicians and Marjory Stoneman Douglas students called for a ban on weapons like the one used to kill 17 people at the Florida high school, and urged voters to kick out lawmakers who oppose the move or who take money from the National Rifle Association.

In a fiery speech, senior Emma Gonzalez demanded national lawmakers do something to prevent mass school shootings.

"We certainly do not understand why it should be harder to make plans with friends on weekends than to buy an automatic or semiautomatic weapon," Gonzalez, who huddled in an auditorium during Wednesday's shooting, said at the rally outside a federal courthouse.

Gonzalez, whose palpable anger burst out in her words, demanded that laws change because she said they have not, while guns have changed.

"Maybe the adults have got used to saying, 'It is what it is,'" she said. "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."

She addressed politicians, saying to those who take campaign donations from the NRA: "Shame on you."

Hundreds of people gathered began to chant, "Shame on you! Shame on you!"

As she ended her remarks, she shouted her disagreement with what she hears from the other side of the gun laws debate.

"Politicians who sit in their gilded house and senate seats funded by the NRA telling us nothing could have been done to prevent this, we call BS!" she said.

"They say that tougher gun laws do not decrease gun violence. We call BS," she cried with the crowd screaming along with the final word.

Read Gonzalez's full remarks

Latest developments

• JetBlue Airways is offering free flights to family members of the shooting victims traveling to Parkland. The airline will also provide free ground transportation via ride-hailing platform Lyft.

• The defense team says NIkolas Cruz will plead guilty if prosecutors don't seek the death penalty, but the state attorney won't rule that out.

• The school district has proposed tearing down the building where the shooting happened, Parkland Mayor Christine Hunschofsky said.

• President Donald Trump and the first lady visited wounded patients at a Florida hospital.

• Three shooting victims remain in hospitals. Broward Health North in Pompano Beach has two patients in fair condition, and Broward Health Medical Center in Fort Lauderdale has one patient in fair condition, according to a statement from hospital officials.

• Math teacher Jim Gard says an administrator sent an email in late 2016, asking to be notified if Cruz came on campus with a backpack. The administrator gave no explanation for the email, Gard said.

Call for ban on some weapons

The man who kicked off the rally, state Sen. Gary Farmer, called for legislation to ban what he called assault weapons and high-capacity magazines and establish a gun registry.

He said people calling for a focus on increasing school security are "missing the point," because even if security were strengthened, people with semiautomatic military-style rifles still could kill at parks and churches.

A crowd at times chanted, "Vote them out!" Some held signs such as "Vote Blue" and "Protect children, not guns."

In a speech to supporters of the President in Dallas, Vice President Mike Pence said Washington will play a role in solutions.

"We will get to the bottom of what happened (in Parkland)," he said Saturday. "And as we speak, the Justice Department is already working with agencies across our government to study the intersection of mental health and criminality. And when President Trump meets with our nation's governors in just a few short weeks, he will make the safety of our nation's schools our top administration priority."

Teacher: 'He fell through the cracks'

Laurel Holland, a retired teacher who had the shooter in her junior year English class in 2016, told CNN that Cruz cursed her out during midterm exams and was suspended.

She said his troubling behavior made her uncomfortable, citing one time when he was caught at school with a gun-related object in his backpack. But she 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 later 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.

Holland, who now lives in North Carolina, said the warning signs were clear enough that when she first heard about Wednesday's shooting, she "knew it was him."

Cruz's disciplinary record shows he was suspended two days for the incident with Holland, one of many times since he started middle school that he faced disciplinary action that included in-school and out-of-school suspensions and detention.

Most of the punishments were for bad language or disrupting class, but one was for fighting and another, in January 2017 while he was still at Stoneman Douglas, was for assault.

The entries on his records indicate a parents conference was often held and sometimes the infractions were just days apart. The records also show Cruz received individual counseling on several occasions.

Will Cruz face death?

Cruz is willing to plead guilty to avoid the death penalty and spare the community from reliving the massacre in a trial, the top public defender said Friday.

Cruz, 19, faces charges of premeditated murder in Wednesday's shooting at the high school in Parkland that left 17 people dead.

Broward County Public Defender Howard Finkelstein, whose office is representing the confessed gunman, said there's no question he killed the 14 students and three staff members.

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

Prosecutors would need to agree not to ask for capital punishment and allow life without parole instead.

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

"Our office will announce our formal position at the appropriate time," Satz said.

Cruz is being held without bond following a video hearing Thursday in a Broward County court.

President visits victims

The Trumps visited hospitalized victims Friday.

The President also went to the Broward County Sheriff's Office headquarters, where he met with first responders who played a role in rescues and the arrest of the shooter.

"What a great job you've done, and we appreciate it very much," he said.

Trump told reporters at Broward Health North that he spoke to victims, and he applauded the efforts of the hospital staff and first responders to save lives.

When asked whether more gun laws were needed to prevent school shootings, he did not respond.

The shooting is at least the seventh at US middle and high schools this year and has reignited a debate over gun control. Some blame congressional inaction for the massacre, while others say now is not the time for such political battles.

FBI says it failed to act on January tip

As the victims' loved ones mourn, more signs are emerging that authorities missed opportunities to intervene weeks before the massacre.

The FBI has acknowledged receiving two tips that appear to relate to Cruz ahead of the shooting. One was a January 5 call to a tip line from someone close to him -- one that the FBI said it failed to act on.

The caller provided 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 information should have been assessed as a "potential threat to life," but the proper protocols weren't followed and the FBI's Miami office was not notified, the agency said.

How to help victims of the Florida school shooting

FBI Director Christopher Wray said the bureau is investigating what happened.

"We have spoken with victims and families, and deeply regret the additional pain this causes all those affected by this horrific tragedy," Wray said in a statement.

The FBI's admission prompted Florida Gov. Rick Scott to call on Wray to resign

Also, 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. An FBI agent confirmed a field officer in Jackson, Mississippi, received the tip and interviewed the person who shared it.

But no additional information was found to help 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.

Social media posts

Cruz's apparent 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 agreed, saying, "Shoot them in the back of head."

At one point in the chat, he wrote, "I think I am going to kill people." After a member told him not to say things like that, he said he was just playing.

In a public post on his Instagram page, Cruz showed what he called an "arsenal" on a bed -- seven guns and body armor. Another post on the page is a view down the barrel of a gun with a holographic sight out a window onto the street.

Cruz was staying with the family of someone he met at the high school after his adoptive parents died, said Jim Lewis, the host family's attorney.

The family knew he had a gun. "They had it locked up, and believed that that was going to be sufficient, that there wasn't going to be a problem," Lewis said.

The family was unaware of any mental illness beyond depression over his adoptive mother's recent death, the lawyer said.

But Gordon Weekes, executive chief assistant of Broward's public defender's office, said Thursday that Cruz is "suffering from significant mental illness and significant trauma."

Before his mother died, Broward sheriff's deputies were called to the Cruz family home 39 times since 2010, according to documents obtained by CNN.

The sheriff's office received a range of emergency calls that included reports of a mentally ill person, child/elderly abuse, a domestic disturbance and a missing person.

There were 20 calls for service over the past "few years" pertaining to Cruz, according to Broward County Sheriff Scott Israel.