Houston Police officers began radioing about "crushing-type injuries" sustained in the crowd at Astroworld shortly after rapper Travis Scott took the stage.

The police radio traffic from the Friday night concert, obtained by the Houston Chronicle, reveals how quickly law enforcement became aware of the rising danger in the throng of concertgoers shortly after the star rapper began performing at the sold-out music festival, which drew about 50,000 people.

Travis Scott performs during the Astroworld Festival. A reported crowd surge contributed to the deaths of nine concertgoers. (Photo by Gary Miller/Getty Images)

The rapper took the stage right around 9 p.m.

"Looks like folks are coming out of the crowd complaining of difficulty breathing, crushing-type injuries," one official said over the police radio around 9:21 p.m., according to the audio obtained by the newspaper. "Seems like the crowd is compressing on itself."

The crowd watches as Travis Scott performs at Astroworld Festival at NRG park on Friday, Nov. 5, 2021, in Houston. Officials declared a "mass casualty incident" just after 9 p.m. during the festival. (Jamaal Ellis/Houston Chronicle via AP)

"I’m at the medical tent," one officer radioed in around 9:30 p.m. "There’s a lot of people trampled and they’re passed out at the front stage."

Later, another officer says, "We’re getting multiple reports of people getting injured. We have another report of cardiac situation with CPR by the stage."

Despite police radio from the night being reported in the media, Houston Police Chief Troy Finner refused to nail down a specific timeline of events during a press conference Wednesday.

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Finner also said Wednesday that police told organizers to shut down the performance when fans in the crowd were administered CPR. Authorities gave word around 10:03 p.m. that the concert was in the process of shutting down, but witnesses say Scott and Drake, the superstar rapper who came on toward the end of Scott's set as a special guest, kept performing.

Scott's attorney's pointed out a safety plan for Astroworld, which stated the festival director and executive producers only could stop the concert. The attorney noted neither of those "is part of Travis’s crew."

A visitor writes a note at a memorial outside of the canceled Astroworld festival at NRG Park on Nov. 7, 2021, in Houston. (Photo by Alex Bierens de Haan/Getty Images)

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Nine people died after sustaining injuries during a reported crowd surge at Astroworld. Scott was performing on stage at the time and has since faced criticism for allowing the show to continue while people were struggling in the crowd.

The rapper claims he didn't know the severity of the situation.

The Associated Press contributed to this report.