Houston Fire Chief Says Officials 'Need to Get to the Bottom of' Deadly Crowd Surge at Astroworld Festival

Houston authorities are still investigating the exact cause of the mass casualty event at Travis Scott's Astroworld Festival on Friday that killed eight people and injured hundreds.

Friday's festival turned deadly when the crowd began surging during Scott's performance. Houston Fire Chief Samuel Peña tells PEOPLE that his department began receiving calls that the situation was "escalating" just before 9:30 p.m. local time.

"At that point, when we started hearing this chatter that people were falling out, that they were having people that were unconscious and they were having trouble getting to them. That's when we requested our resources because we knew that this was going to escalate," Peña says.

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Within 10 minutes of calling for additional resources, the Houston Fire Department had declared a level two mass casualty event.

"After the mass casualty was initiated, then [people] started having cardiac arrests," Peña tells PEOPLE, adding that emergency personnel also began administering Narcan to some individuals (a treatment typically used to counteract a suspected opioid overdose).

While officials haven't determined exactly what went wrong, Peña tells PEOPLE: "For whatever reason, the crowd decided to try to push towards the stage. When they started to move closer and push towards the stage, the ones that were up front near the barriers were not able to make their way out."

"We need to get to the bottom of what caused people to start surging..." he says. "But more than that, what's been on my mind is: how could it have been stopped? From my perspective, everybody at that concert had a responsibility, including the crowd, but certainly the security and even the artists. They have a lot of control over the crowd. I'm not saying that this is the answer, but I've seen it in other instances where the artist pauses the show, turns on the lights and says, 'Hey, we need to address whatever before we move forward.' "

A source close to Scott tells PEOPLE the rapper was unaware of the magnitude of the situation. "The lights were shining in his eyes and he couldn't see what was happening," says the source. "He thought someone had just passed out, which happens during concerts."

This is not the first time that fans have been injured at Astroworld Festival. In 2019, three people were hospitalized after fans rushed the gates to the event shortly before the event opened, according to Rolling Stone. There was no festival in 2020 due to the COVID-19 pandemic.

Due to the incident in 2019 — as well as other tragedies at similar large-scale events — Peña tells PEOPLE his department positioned an incident commander on the scene to "monitor communications" between the event's private security and medical personnel in case of emergency.

For more on the tragedy at Astroworld, listen below to our daily podcast on People Every Day.

Around 50,000 people were in attendance at NRG Park for Friday's festival. Peña says that local officials are always on high alert for large-scale events, "because when we have a large number of people congregated in one area, the possibilities are endless."

John Hilgert, 14; Brianna Rodriguez, 16; Franco Patiño, 21; Axel Acosta, 21; Jacob Jurinek, 21; Rudy Peña, 23; Madison Dubiski, 23; and Danish Baig, 27, have been identified as the eight victims who died in the tragedy.

Peña tells PEOPLE that six others are still hospitalized, with five in the intensive care unit. Of those in the ICU, two are "in serious, critical condition." He did not release the ages of those who still remain hospitalized.

After Friday's tragic event, two eyewitnesses told PEOPLE they feared for their lives amid the chaos on the scene. One attendee explained that it was "getting scary" prior to Scott taking the stage, adding that it became even more terrifying once his set began.

"When Travis finally comes out, people are moving even more, getting rowdier," she said. "It just felt like so much pressure as people got excited … I was literally getting squished, very uncomfortable. It felt like I was going to die."

"I couldn't enjoy it because I seriously could not breathe," the concertgoer added. "I had to turn away from the stage at points to just breathe. My shoulders were in people's back, I was pressed against people."

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In a statement shared on Saturday, Scott said he was "absolutely devastated" by the events that took place.

"My prayers go out to the families and all those impacted by what happened at Astroworld Festival," the rapper posted on Twitter. "Houston PD has my total support as they continue to look into the tragic loss of life."

He continued, "I am committed to working together with the Houston community to heal and support the families in need. Thank you to Houston PD, Fire Department and NRG Park for their immediate response and support."