At least eight people have died and scores of others injured in what authorities described as a "mass casualty" incident on the opening night of a popular music festival here in Texas attended by some 50,000 fans of American rapper Travis Scott.

The sold-out concert by Scott at the Astroworld Festival in Houston had to be cancelled immediately after people started falling after the massive crowd began "to compress toward the front of the stage" around 9:00-9:15 PM (local time) on Friday, CNN reported.

Multiple fans were trampled as hundreds rushed the event's perimeter. Once inside, some people began climbing onto portable toilets as security personnel worked to try and contain the crowd, ABC 13 news website reported.

"We had scores of individuals that were injured," Houston Fire Chief Sam Pena said during a news conference early on Saturday morning.

"The crowd began to compress toward the front of the stage, and people began to panic," Pena said.

Describing what unfolded as a "mass casualty" incident, the fire chief said that 17 patients were rushed to local hospitals.

More than 300 people were treated at the field hospital set up near the festival, Pena said, adding that the concert drew about 50,000 attendees.

So far, eight people have died and hundreds of others injured during the opening night of the popular weekend music festival, authorities said.

Astroworld organisers did not immediately respond to CNN's request for comment early Saturday morning.

Organised by rapper Scott, the third annual festival featuring multiple acts was scheduled to run from Friday through Saturday, according to the event's website. The view from SkyEye overhead Friday night showed the heavy police and fire department activity in the area of the event as organisers ended it early.

The organisers, rapper Scott and LiveNation, stopped the show when it was apparent that multiple people were hurt, according to Houston Police Chief Troy Finner, ABC 13 reported.

The crowd disregarded metal detectors and security guards who were checking bags.

Members of the Houston Police Department's Mounted Patrol Unit were also on scene and worked to contain the chaotic scene.

The event's tickets sold out within an hour of going on sale back in May.

Scott, the popular rapper and organiser, launched the Astroworld Festival in 2018. Like most other large events, it was canceled in 2020 due to the COVID-19 pandemic, the report added.