At least eight people have died in a crowd surge during a Travis Scott concert at Astroworld Festival in Houston.
The crowd had moved closer to the stage while Scott, who runs the festival, was performing on the opening night.
Houston fire chief Samuel Pena said hundreds of others were injured and the show was called off shortly after the crush occurred.
Mr Pena said when the crowd began to move forward it “caused some panic, and it started causing some injuries”, NBC News reported.
He said people “began to fall out, become unconscious, and it created additional panic”.
Chief Lt Larry Satterwhite from Houston police was near the front when the tragedy unfolded.
“It seems like it happened with just over the course of a few minutes – suddenly we had several people down on the ground experiencing some type of cardiac arrest or some type of medical episode,” he said.
“We immediately started doing CPR.”
The fire and rescue service took 17 people to nearby hospitals, with 11 of them in cardiac arrest, CBS News affiliate KHOU 11 News Houston said.
A crowd of 50,000 people showed up for the two-day festival.
The second day has now been cancelled.