A female Cirque du Soleil performer died over the weekend in Las Vegas when she fell during the performance.

The performer known as "Sassoon" on stage was 31-year-old Sarah Guillot-Guyard. She was pronounced dead on Saturday shortly before midnight.

The formal cause of her death has yet to be released after a coroner examines the Paris-born performer's body.

Audience members witnessed the fall of Guillot-Guyard who was one of the several performers who will do a high-flying stunt in the final scene.

Guillot-Guyard was suspended from a safety wire when she slipped free from it and dropped on the unseen pit below the performers.

"She was being hoisted up the side of the stage and then just plummeted down," said Dan Mosqueda, a member of the audience who witnessed the fall. "Initially, a lot of people in the audience thought it was part of the choreographed fight. But you could hear screaming, then groaning, and we could hear a female artist crying from the stage," he said.

The curtains were brought down immediately when Guillot-Guyard was rushed to the hospital. Cirque du Soleil founder Guy Laliberte said in a statement that they are "working with the appropriate authorities and have offered our full cooperation".

"We are reminded, with great humility and respect, how extraordinary our artists are each and every night. Our focus now is to support each other as a family, "he said.

Guillot-Guyard, an acrobatic performer for the past 22 years, was part of the original cast of Cirque du Soleil's long-running show at the MGM Grand, "Ka". This is the first time in the troupe's 30-year history that a performer died during the show.