HOUSTON (NewsNation Now) — Investigators worked Sunday to determine how eight people died in a crush of fans at a Houston music festival, as families mourned the dead and concertgoers recounted the horror and confusion of being trapped in the crowd.

Authorities planned to use videos, witness interviews and a review of concert procedures to figure out what went wrong Friday night during a performance by rapper Travis Scott. The tragedy unfolded when the crowd rushed the stage, squeezing people so tightly they couldn’t breathe.

“Before Travis even came on, there was not a centimeter between people, they were just shoving, pushing,” Billy Nasser said on NewsNation Prime Sunday. “If you put your arms up, you couldn’t put them back down … once the first song started, people (started) drowning..”

Nasser, 24, had traveled from Indianapolis to attend the concert. He said he tired to help some of the victims.

“Kids were just dead left and right,” Nasser said. “And the way the barricade was set up, it was trapping people in there and they couldn’t get out.”

Over the weekend, a makeshift memorial of flowers, votive candles, condolence notes and T-shirts, including a Scott shirt, took shape outside at NRG Park.

The dead, according to friends and family members, included a 14-year-old high school student; a 16-year-old girl who loved dancing; and a 21-year-old engineering student at the University of Dayton. The youngest was 14, the oldest 27.

Houston officials did not immediately release the victims’ names or the cause of death, but family and friends began to name their loved ones and tell their stories Sunday.

Two Naperville, Illinois natives were among those killed, according to NewsNation affiliate WGN.

Franco Patino and Jacob Jurinek were best friends since elementary school.

Patino was 21 and was a junior at the University of Dayton. His family said they found out about his death when the hospital called his mom from his cellphone. Loved ones remembered him as a selfless person who always put others before himself.

Jacob Jurinek’s family says he was known for his boundless energy and contagious enthusiasm.

“We are all devastated and are left with a huge hole in our lives,” said Jacob’s father, Ron Jurinek, “We’re comforted by the fact that hundreds of people Jake touched over the years will carry a piece of his spirit with them.”

A total of 13 people remained hospitalized Sunday. Their conditions were not disclosed. More than 300 people were treated at a field hospital at the concert.

City officials said they were in the early stages of investigating what caused the pandemonium at the sold-out Astroworld festival, an event founded by Scott. About 50,000 people were there.

Authorities said that among other things, they will look at how the area around the stage was designed.

“They should have stopped the show very early on,” Nasser said.

Steven Adelman, vice president of the industry group Event Safety Alliance, which was formed after the collapse of a stage at the Indiana State Fair in 2011 killed seven people, helped write industry guidelines widely used today.

He said investigators will examine the design of the safety barriers and whether they correctly directed crowds or contributed to the crush of spectators. He said, too, that authorities will look at whether something incited the crowd besides Scott taking the stage.

Adelman said another question is whether there were enough security staffers present, noting there is a nationwide shortage of people willing to take low-wage, part-time security gigs.

“Security obviously was unable to stop people. Optically, that’s really bad-looking,” he said. “But as for what it tells us, it’s too early to say.”

Contemporary Services Corp., headquartered in Los Angeles, was responsible for security staff at the festival, according to county records in Texas. Representatives for the company — which advertises online as being “recognized worldwide as the pioneer, expert and only employee owned company in the crowd management field” — did not immediately respond to emails and phone messages seeking comment.

Houston police and fire department officials said their investigation will include reviewing video taken by concert promoter Live Nation, as well as dozens of clips from people at the show.

Officials also planned to review the event’s security plan and various permits issued to organizers to see whether they were properly followed during the event. In addition, investigators planned to speak with Live Nation representatives, Scott and people who were at the concert.

Izabella Ramirez of Texas City was celebrating her 21st birthday and said that once Scott came on stage, no one could move.

“Everybody was squishing in and people were trying to move themselves to the front. You couldn’t even lift up your arms,” Ramirez said.

Ramirez said a security guard pulled her over the barricade, while her date, Jason Rodriguez, lifted her up.

“Everyone was yelling for different things. They were either yelling for Travis or they were yelling for help,” Rodriguez said.

On video posted to social media, Scott could be seen stopping the concert at one point and asking for aid for someone in the audience: “Security, somebody help real quick.”

In a tweet posted Saturday, Scott said he was “absolutely devastated by what took place.” He pledged to work “together with the Houston community to heal and support the families in need.”

“I don’t think Travis is to blame,” Nasser said. “I think he tried to help out with the crowd. It was just overcrowding and just bad organization by the festival.”

The rapper is facing at least one lawsuit by a concertgoer who was injured .

The Associated Press and NewsNation affiliate WGN contributed to this report.