HOUSTON (AP) - Investigators are expected to examine the design of safety barriers and the use of crowd control in determining what led to a crush of spectators at a Houston music festival that left eight people dead and hundreds more injured.

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.

Billy Nasser, 24, who had traveled from Indianapolis to attend the concert, said about 15 minutes into Scott’s set, things got “really crazy” and people began crushing one another. He said he “was picking people up and trying to drag them out.”

Nasser said he found a concertgoer on the ground.

“I picked him up. People were stepping on him. People were like stomping, and I picked his head up and I looked at his eyes, and his eyes were just white, rolled back to the back of his head,” he said.

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

Michael Suarez, 26, visited the growing memorial after the concert.

“It’s very devastating. No one wants to see or hear people dying at a festival,” Suarez said. “We were here to have a good time - a great time - and it’s devastating to hear someone lost their lives.”

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.

Thirteen people remained hospitalized Sunday. Their conditions were not disclosed. Over 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.