HOUSTON — While authorities continue to investigate the tragedy at the Astroworld festival in Houston, a timeline of what happened became clearer on Monday.
Officials said the concert continued for nearly 40 minutes after Houston police declared the situation a mass casualty event.
What led up to the concert? What unfolded, when and where?
Here's a timeline of Friday's events, based on what we know:
3:30 a.m. - Fans begin lining up
Fans began lining up to enter the Astroworld grounds well in advance. A concert worker told the New York Times that an estimated 1,000 people were already in line waiting for the gates to open in the early morning hours Friday.
That’s the main entrance highlighted here, in the bottom right corner of the map:
10 a.m. - Gates open
The gates opened at 10 a.m. Friday. And concertgoers rushed through, some jumping over barricades. One video from the NRG entrance showed a crowd of fans trampling a fence as they rushed onto the grounds.
The crowds grew quickly as the hours passed.
Aerial video from Friday night shows the massive crowd at the concert.
A medical plan obtained by the New York Times showed that the concert’s medical provider called for a main medical tent with two doctors, six nurses, two paramedics, and nine EMTs.
By 8:15 p.m., the medical staff was overwhelmed helping, a venue medic told the New York Times.
Then, the crowd surge worsened.
Before 9 p.m. - Countdown to Travis Scott
A countdown timer began about 30 minutes before Travis Scott’s scheduled performance on the “Chills Stage” at NRG Park.
An ICU nurse told our partners at CNN that people were compressed up against each other "pushing forward and backward."
Houston Fire Chief Samuel Peña said the crowd surged from the sides – not front to back.
9:30 p.m. - Ambulance responds within the crowd
The music stopped as an ambulance made its way through the crowd after the first reports of people getting hurt in the crowd.
Video footage showed Scott stopping his concert and asking, "What is that?" as the ambulance entered the crowd.
9:38 p.m. - Mass casualty event declared
A mass casualty event was declared. But the concert kept going, except for two other short pauses, according to concertgoers.
Video from the concert did show Scott stopping the concert and asking for someone's help when he saw someone in the crowd in distress.
Around 10:10 p.m. - The performance stops
The performance was officially stopped at around 10:10 p.m., more than 30 minutes after a mass casualty event was declared.
Even after the music stopped, emergency medical crews had to make their way through the crowd to get to patients.
Houston fire Chief Samuel Peña said the exits weren’t blocked. But since there were so many people in attendance, those tightly packed near the stage couldn’t get out.