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HOUSTON (NewsNation Now) — Details are still being pieced together about what happened at the Astroworld Festival in Houston that left eight people dead and dozens injured.

City officials Tuesday were in the early stages of investigating what caused the chaos at the Travis Scott concert as a prominent local official called for a separate, independent review of the tragedy.

Here is what we know so far:

2 p.m. local time Friday: Concertgoers arrive

Concertgoers rush through the gates of Astroworld, the yearly festival founded by Scott in 2018. During the rush into NRG Park, the VIP security checkpoint is destroyed and at least one person is hurt.

8:30 p.m.: Countdown to Scott’s set starts

A 30-minute countdown begins at the stage where Scott is set to perform. As a timer clicked down to the start of Scott’s performance, the crowd pushed forward.

9 p.m.: Scott goes on stage, crowd surges

As Scott begins his set, the crowd rushes forward. According to eyewitnesses, people start passing out as Scott performs his first song.

9:30 p.m.: Reports of people injured in the crowd

Houston Fire Department receives reports that people are hurt in the crowd. Firefighters send help to the scene. At the same time, Houston police officials said they told the show’s producers that people were going down.

9:38 p.m.: Mass casualty event declared

Houston Fire Department says they declared the event a “mass casualty event.” The department reported it took two minutes to get to the scene and make contact with the first patient. Concertgoers say they were crying out for help but emergency responders couldn’t hear them over the loud music.

10:10 p.m.: Scott stops performing

Scott stops performing. Some concert attendees say Scott finished his full planned set before stopping.

Houston Police Chief Troy Finner has defended how long it took for the concert to be called off after the first signs of trouble. The police chief said his department immediately notified concert organizers after noticing that attendees were “going down.” The event was called off 40 minutes later after discussions that included the fire department and NRG Park officials.