CNN  — 

Moments before a 17-year-old unleashed gunfire at Iowa’s Perry High School, killing a sixth grader and wounding seven other people, the student is believed to have posted a foreboding TikTok video.

On the morning Dylan Butler opened fire, a TikTok post believed to be from the shooter shows him inside a school bathroom posing with a blue duffel bag, captioned: “Now we wait.”

The song “Stray Bullet,” by the German band KMFDM, accompanies the post – which has been removed from the platform. The band’s lyrics have also been cited by the student gunmen who carried out the 1999 massacre at Columbine High School in Colorado, where 13 victims were killed, CNN has reported.

The gunman in Iowa “made a number of social media posts in and around the time of the shooting” on Thursday morning, said Mitch Mortvedt, assistant director of the Iowa Department of Public Safety Division of Criminal Investigation. “Law enforcement are working to secure those pieces of evidence,” he added.

New details also are emerging about whether Butler may have been bullied, though his motive might never be confirmed because he is dead. He was found with a self-inflicted gunshot wound, Mortvedt said.

Still, investigators are trying to determine why Butler entered the school with a pump-action shotgun and small-caliber handgun, Mortvedt said. Officers also discovered a rudimentary explosive device after the killer went on the deadly rampage before classes started on the first day back to school since winter break.

Investigators also have “seized large volumes of digital and social media evidence that will take time to review,” the Iowa Department of Public Safety said in a news release Friday. The Division of Criminal Investigation’s report “will be turned over to the Dallas County Attorney’s Office to determine what additional course of action, if any, should be undertaken,” according to the department.

The attack marked the second shooting on a US school property in just the first few days of this year. Last year, more than 80 such shootings erupted on school grounds nationwide, a CNN analysis shows. The US this year also has suffered six mass shootings in which at least four victims are shot, according to the Gun Violence Archive.

Now, survivors and witnesses in a small city near Des Moines are echoing the same sentiment as others who have suffered the terror of mass shootings in America:

“It doesn’t feel real,” student Rachael Kares told CNN. “This is like one of those things where you see on TV and you’re like that never gonna linger its way toward my community, but it does happen. It’s really real.”

Gunman’s parents ‘do not understand’

While the community struggles to find answers, so do the gunman’s parents.

“As the minutes and hours have passed since the horrors our son Dylan inflicted on the victims, the Perry School and the community, we have been trying to make sense out of the senseless,” Jack and Erin Butler said Monday in a statement obtained by CNN affiliate KCCI. “We are simply devastated and our grief for the deceased, his family, the wounded and their families is immeasurable.”

“When we dropped off our son for school on January 4th, we had no inkling he intended the horrible violence he was about to inflict,” the parents said in the statement provided by the office of their attorney, Mark Powell.

“On the way to school Dylan had been discussing with us of future plans and it felt like he was ready to get back to school after Christmas vacation and the start of a new semester. Dylan’s sister, our daughter, was in the school at the time of the shooting. We simply do not understand how this could happen and why Dylan chose to do what he did.”

The Butlers said their grief over the slain victim is compounded by the loss of their own son.

“We would never wish the harm and pain that Dylan’s actions caused on anyone and we could not have imagined that Dylan would carry out such a heinous act. Our family has to mourn and bury our son, and live with this terrible legacy,” the gunman’s parents said.

“We cannot repay the grace we have been shown in public and private. We are helping authorities and will continue to help to provide answers to the question of why our son committed this senseless crime. Through God’s grace we hope the answers can be found and that those answers will prevent other young people from harming others.”

‘Everything just went to chaos’

As students dug into cafeteria breakfasts and wrapped up band practice Thursday morning, one of their peers stepped into the building with two guns and began firing – sending kids and teachers scrambling for safety.

The shooting happened before the classes at Perry High School, which shares a campus with Perry Middle School. “It’s our understanding that there was a breakfast program going on, so there may have been students of different grades … in the school at that time,” Mortvedt said.

At first, the gunshots were mistaken by some as disruptive noise – a popped balloon, a dropped bag – two witnesses said.

Then the horror of reality set in.

“The whole cafeteria went silent,” high school student Angie Orellana told CNN. “Then more shots continued, and everything just went into chaos. I just saw the principal start running and all my friends, and I just got out of there.”

Nearby, Kares was wrapping up jazz band practice when she heard four shots resonate through the hall. A burning smell lingered in the air. Then another shot came.

“Our band teacher looked at us, and he just goes, ‘Run!’” she told CNN’s Anderson Cooper. “None of us hesitated. We just all got up and ran.”

Kares and her friends ran outside, trying to get “anywhere away from school,” she said. “We just kept going.”

Perry High School Principal Dan Marburger tried to save students by talking to and distracting the shooter during the deadly attack, his daughter Claire Marburger posted on social media.

Perry Community School District
Principal Dan Marburger was wounded in the shooting.

“As I heard of a gunman, I instantly had a feeling my Dad would be a victim as he would put himself in harms way for the benefit of the kids and his staff,” she wrote. “It is absolutely zero surprise to hear he tried to approach and talk Dylan down and distract him long enough for some students to get out of the cafeteria.”

The principal was wounded in the shooting and underwent surgery.

More than 150 federal, state and local officers arrived to find students and staff sheltering in place or running from the building, Mortvedt said.

Inside, officers discovered the wounded gunman, as well as the explosive device, which authorities rendered safe, Mortvedt said.

The gunman’s friends describe bullying

While the motive in the attack remains unclear, two teens described as friends of Butler said he had been bullied since elementary school, they told ABC News.

“He got tired, he got tired of the bullying, he got tired of the harassment,” one friend told ABC News.

“We tried to be there when he needed us,” another friend tearfully told ABC News. “Clearly, we weren’t there for him enough.”

CNN is reaching out to authorities about whether the bullying claims have turned up in their investigation.

Slain student named as community mourns

The Perry Middle School student killed in the shooting has been identified as 11-year-old Ahmir Jolliff, the Iowa Department of Public Safety said in a Friday news release. He was shot three times, authorities said.

The public safety department updated the total of wounded to seven on Friday. “Three of the victims are school staff members and four are students,” the release stated.

Marburger “suffered multiple gunshot wounds,” authorities said. “The investigation thus far confirms Principal Marburger acted selflessly and placed himself in harm’s way in an apparent effort to protect his students,” according to the release. He has worked at schools in Perry for at least 25 years, according to the Perry Community School District.

“This senseless tragedy has shaken our entire state to the core,” Iowa Gov. Kim Reynolds said Thursday. “I want you to know that we’ll work tirelessly to get the answers so that we can prevent it from happening again.”

Mourners grieved the loss of the slain sixth grader, who was “the sweetest boy – the one you want your kids to be friends with,” Perry resident Jessica Conrad told CNN. Some gathered Thursday night for a vigil at a local park, clutching candles as speakers shared messages of strength, sympathy and unity.

Scott Olson/Getty Images
Community members gather for a candlelight vigil Thursday night.

“Even though we are in a tiny town, the whole world is wrapping its arms around us tonight,” said former Perry school student Andrea Niemeyer, who noted she’s received condolences from as far as Washington state.

“We’ll get through this because we have each other,” she added.

Some expressed shock and disbelief, including a mother who said her husband tried to drop their children off early at the school but was turned away. “I just found all throughout the morning as the time progressed that I would kind of lose my breath as I realized how lucky that was,” Mindy Farmer said.

Later in the day, the question, “What now?” began to weigh on her, Farmer said. “I think you can start to feel kind of powerless.”

Several vigil attendees offered up prayers, including local pastor Kathy Benton, who prayed for the students who “are going to be dealing with the memories and the sounds and everything.”

“We pray for healing of their minds,” she said. “We pray for healing of their emotions.”

This story has been updated with additional information.

CNN’s Caroll Alvarado, Melissa Alonso, Christine Sever, Andy Rose, Hannah Rabinowitz, Amy Simonson, Evan Perez, Aaron Pellish, Sharif Paget, Dakin Andone and Christina Maxouris contributed to this report.