Eight people were killed and several others injured after concert-goers surged towards the stage.
An estimated 50,000 people showed up for the two-day event, which has now been called off.
Distressing footage on social media shows paramedics performing CPR on several people on the floor.
A video has emerged of the rapper stopping his set and asking security at his festival to help fans in the audience during the fatal crash.
In the video Scott, who runs the festival, could be seen pausing his concert, saying: ‘Somebody has passed out right here, do not touch him, do not touch him.’
Authorities said the tragic incident happened as fans ‘began to compress’ to the front of the stage while Scott was performing, at around 9:15 PM local time.
Fire Chief Sam Peña said the rush caused some panic, and this started causing some injuries.
‘People began to fall out, become unconscious, and it created additional panic,’ Peña said.
Pena: ‘mass casualty incident, saying 17 patients were transported to local hospitals, 11 of whom were in cardiac arrest.
In addition, more than 300 people were treated at the field hospital set up near the festival.
Those injured included children ‘as young as 10’, authorities said.
The scenes unfolded on the opening night of the third annual Astroworld music festival.
Astroworld music festival as being held at NRG Park in the city of Houston.
The video showed hundreds of people rushing through a VIP entrance to the event.
People were knocking over metal detectors and ignoring security personnel before officers secured the gates on horseback.
Event promoters had arranged for medical units to be on the scene at the festival.
However, once the crowd surge began, those units were ‘quickly overwhelmed,’ authorities said.
Houston Police Executive Assistant Chief Larry Satterwhite was near the front of the crowd and said it seemed the surge ‘happened all at once.
‘Suddenly, we had several people down on the ground, experiencing some cardiac arrest or some medical episode,’ he said.
‘And so we immediately started doing CPR and moving people right'.
'that is when I went and met with the promoters and Live Nation, and they agreed to end early in the interest of public safety.’
No cause of death was given for the eight confirmed deaths, pending the medical examiner’s investigation.
The victims had not been identified as of early Sunday local time.
The police chief leading the investigation asked people not to speculate but said officers were investigating rumours ‘people were injecting drugs’.
However, unfortunately, we have none of the answers tonight,’ said Houston Police Chief Troy Finner.