(CNN) As investigators track the gun purchases of Florida school shooter Nikolas Cruz, dozens of students and staff from the site of the massacre will board buses late Tuesday, bound for the state capital.

In Tallahassee, they hope to talk to legislators about school safety and gun control on Wednesday, determined to ensure that the deaths of their 17 classmates and teachers last week at Marjory Stoneman Douglas High School in Parkland bring about change.

School walkouts and a march are scheduled in the coming weeks, and a CNN town hall with victims' classmates, parents and the community is set for Wednesday in Sunrise, Florida.

"They can change the world, and we can only go with them," Darren Levine, a Stoneman Douglas High teacher, said of the school's students at an anti-violence rally in Delray Beach, Florida -- one of at least three across the country on Monday.

Hours earlier Monday, Cruz made a brief appearance in court for a procedural matter.

A law enforcement source briefed on the investigation told CNN that Cruz had obtained at least 10 firearms, all of them rifles. Investigators are trying to track the purchases, which Cruz appears to have made in the past year or so, the source said.

Cruz bought two weapons from Gun World of South Florida in Deerfield Beach, said Kim Waltuch, the store's CEO. She would not provide details on the types of guns he purchased or on the time frame, but said the sales followed normal protocol for Florida firearms purchases.

Meanwhile, one of Cruz's victims, Anthony Borges, 15, continued his recovery. He's one of four patients who remain hospitalized after Wednesday's massacre in Parkland. He was shot five times, according to the Broward County Sheriff's Office.

On Sunday, the teen remained in a bed, his face swollen and his body tethered to IV and oxygen tubes.

"Fortunately, he is recovering -- but has a long road ahead with more surgeries needed," according to a Broward County Sheriff's Office Facebook post.

Anthony helped protect his classmates, closing and locking a door to a classroom, according to a verified GoFundMe account that, as of late Monday morning, had raised more than $275,000 late Monday . As Anthony blocked the door, Cruz fired through it, hitting Anthony in the back and in both legs, shattering his thigh bone, according to the account's description.

Latest developments

Rallies against gun violence in Florida, California and Washington, D.C.: The names of victims were read out loud at a rally in Delray Beach. In Los Angeles, protesters, including many young children gathered in Pershing Park, chanted "throw them out," referring to politicians who support the National Rifle Association. "Apparently when a school shooting happens, it's just another day in America and nobody cares," said Sophie Peterson, a student. "Students and teachers are dying and that is not OK." In Washington, teen The names of victims were read out loud at a rally in Delray Beach.In Los Angeles, protesters, including many young children gathered in Pershing Park, chanted "throw them out," referring to politicians who support the National Rifle Association. "Apparently when a school shooting happens, it's just another day in America and nobody cares," said Sophie Peterson, a student. "Students and teachers are dying and that is not OK." In Washington, teen demonstrators lay on the ground in front of the White House in solidarity with the 17 victims. Others carried flags and posters.

Details on shooter's behavior: A 2016 Florida Department of Children and Families report says that after a breakup with a girlfriend, Cruz began cutting his arms. He also announced plans to buy a gun, put racial slurs and hate symbols on his backpack and suffered from depression, attention deficit hyperactivity disorder and autism, the report said. Despite Cruz's behavior, the report concluded the "final level of risk is low."

Cubs star speaks out: Marjory Stoneman Douglas alum and Chicago Cubs first baseman Anthony Rizzo said during a news conference that he had visited kids in the hospital after the shooting. He also issued a call for change, saying, "No one right now feels comfortable on a daily basis sending their kid to school not knowing if they're going to see them again."

Host family saw no clues: Kim and James Snead, who took in Cruz after his adoptive mother died in November, tell ABC's "Good Morning America" that : Kim and James Snead, who took in Cruz after his adoptive mother died in November, tell ABC's "Good Morning America" that Cruz was polite and "seemed normal." Despite reports of what authorities say was a disturbing social media footprint, James Snead said, "We knew he had one Instagram account. ... The other ones he had, we had no idea about."

Funerals scheduled for this week: Among those being laid to rest this week are Alaina Petty, 14, and Luke Hoyer, 15, whose services were held Monday morning, and Cara Loughran, 14, whose service is Tuesday. Cara's aunt, Lindsay Fontana, said on Facebook the day after the shooting that her niece was an "excellent student" who loved the beach. Alaina's family described her as a "vibrant and determined young woman" who volunteered in cleanup and rebuilding efforts after Hurricane Irma.

Remembering the victims: Vigils were held Monday for the Parkland shooting victims in nearby Miramar and Coral Springs, Florida.

Alleged school threats elsewhere: A 14-year-old Norfolk, Virginia , middle school student was the latest person to be arrested Monday for threatening to harm classmates, according to Norfolk police. The student faces a felony charge and is accused of making threats of death or bodily injury to a person or persons on school property, police said. Since the massacre in Parkland, there have been at least a dozen reports of other incidents involving a threat to a school or a weapon on campus throughout the country. In some of these events, the schools have closed or gone into lockdown.

Students mobilize

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In the aftermath of the shooting, many students who survived the bloodshed say they can no longer endure inaction on the issue of gun control. Just days after surviving the ninth-deadliest shooting in modern US history , several students have given powerful speeches and compelling TV interviews, voicing their desire to break the loop of massacres.

Some have gone on social media, vocal about what they experienced and what action they want to see from those in power. They're demanding that state and federal lawmakers step up and do something.

They're also coming for the NRA and any politician who takes money from the powerful gun lobby. The NRA did not return CNN's call seeking comment.

"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," said junior Cameron Kasky, announcing a March 24 demonstration in Washington.

They plan to converge at the nation's capital next month and have asked supporters who can't make it to stage marches in their own communities, according to a mission statement for March For Our Lives

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

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

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Trump tweet angers students

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Students who survived the shooting laid into President Donald Trump after he seemed to blame the FBI's failure to follow up on a report about the school shooter on the agency's attention and resources on the Russia investigation.

On Saturday, Trump tweeted, "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 - there is no collusion. Get back to the basics and make us all proud!"

The President's tweet caused considerable outrage online, including among apparent survivors of the shooting. One wrote: "Oh my god. 17 OF MY CLASSMATES AND FRIENDS ARE GONE AND YOU HAVE THE AUDACITY TO MAKE THIS ABOUT RUSSIA???!! HAVE A DAMN HEART. You can keep all of your fake and meaningless 'thoughts and prayers'."

As the investigation continues, a review has been ordered by Attorney General Jeff Sessions into how a tip to the FBI about Cruz was missed and how the agency responds to indications of potential violence.

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

The FBI failed to act on a January 5 tip 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.

A video blogger also 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, said Robert Lasky, FBI special agent in charge of the Miami division.

Report: Cruz cut himself after breakup, had 'hate signs' on backpack

CNN obtained a 2016 report from the Florida Department of Children and Families that said Cruz engaged in self-destructive behavior after a breakup with a girlfriend.

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DCF spoke with the teen's now-deceased mother, Lynda Cruz, who told them he suffered from depression, ADHD and autism. After the breakup, she said, he began cutting his arms and posting it to Snapchat. Previously, Cruz had put a Nazi symbol on his backpack, and "had hate signs on a book bag, stating, 'I hate n*****s,'" according to the report.

"(Lynda Cruz) stated (Nikolas) started cutting only after (Nikolas) and the girl broke up. She stated that there has never been any issues with other races or issues with racism in the family or (Nikolas)," the report states. "She stated that she even asked (Nikolas) why would he draw something like that and (he) claimed not knowing what it was."

The DCF report ultimately found that the "final level of risk is low" because Cruz was residing with his mother, receiving in-home mental health services and attending school.

In a statement Monday, DCF Secretary Mike Carroll said the agency "is absolutely heartbroken and disgusted by last week's tragedy."

"Once we learned that the shooter had involvement with the agency in 2016, we immediately began the process of asking a court to release these records detailing DCF's only involvement with this person. We also conducted a thorough review to confirm that all processes and procedures were followed. In these investigations, DCF relies on the expertise of mental health professionals and law enforcement and these records show that DCF took the steps to involve these partners in investigating this alleged abuse. Cruz was receiving mental health services before, during, and after our investigation was closed, he was living with his mother, and attending school," Carroll's statement said.

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.

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State Attorney Michael J. Satz said Saturday 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."

Cruz was being held without bond in Broward County. He wore a red jumpsuit, with his wrists shackled to his waist, when he appeared in court Monday for a hearing on the sealing of certain documents in the case. Cruz didn't speak publicly, answering only his public defender's questions, and looked down for most of the hearing.

Another court had sealed documents pertaining to the defense team's "access to their own client's person," Judge Elizabeth Scherer said, adding that she saw no reason prosecutors would oppose the move. Future such motions will be handled by her court, she said.