At least eight people were killed and many were injured in a crowd surge during the opening night of the Astroworld music festival on Friday in Houston, officials said.
Houston Fire Chief Samuel Peña confirmed the casualty figures at an early morning news conference outside NRG Park.
Peña said that at around 9 p.m. the crowd that had gathered for a performance by rapper Travis Scott began to push toward the front of the stage, causing panic and injuries.
People began to fall unconscious, and the mayhem escalated until 9:38 p.m. when a "mass casualty incident" was triggered, he said.
The fire department transported 17 people to hospitals, and 11 of those transported were in cardiac arrest.
It was not yet clear what caused the disaster and the deceased had not been identified as of early Saturday.
"I think it's very important that none of us speculate. Nobody has all the answers tonight," Houston Police Chief Troy Finner said. "If you don't have facts, if you don't have evidence, I'm not going to speak against that. We have hurting families out here."
Finner added that the organizers and Scott were both cooperating with police.
"It happened all at once. It seemed like it just happened ... over the course of just a few minutes," said Houston Police Executive Assistant Chief Larry Satterwhite.
"Suddenly we had several people down on the ground, experiencing some type of cardiac arrest or some type of medical episode," he added.
The Houston Chronicle said Scott stopped multiple times during his 75-minute performance when he spotted fans in distress near the front of the stage.
He asked security to make sure they were OK and help them out of the crowd. Emergency vehicles, lights and alarms flashing, cut through the crowds several times.
Astroworld is a two-day music festival that was scheduled to take place Friday and Saturday. The event was sold out, according to the Astroworld website. Saturday's performances have been canceled.
