At least eight people were killed and many others injured in a crush at the opening night of Houston's Astroworld music festival triggered by a surge of fans pushing toward the stage.
Authorities set up a reunification center at a nearby hotel for families who had not heard from loved ones.
Houston Fire Chief Samuel Peña confirmed the casualty figures from Friday night's disaster at a news conference early Saturday outside NRG Park.
A sold-out audience of about 50,000 people attended the first day of the festival featuring rapper Travis Scott.
''What we do know is that at approximately 9 o'clock, 9:15, the crowd began to compress towards the front of the stage and that caused some panic and started causing some injuries. People began to fall out, become unconscious. And it created additional additional panic.''
The fire department transported 17 people to hospitals, and 11 of those were in cardiac arrest.
It was not yet clear what caused the disaster and an investigation is underway.
Houston's Police Chief told reporters that the organizers and Scott were both cooperating with police.
Astroworld Fest said in a Twitter message it was canceling Saturday's second day of the festival.