The LA Times cited witnesses as saying that Guillot-Guyard was suspended from the ceiling by a wire during in the fight scene of "Ka" when she fell and hit the ground.
She fell into the pit below the stage, out of sight of audience members, and one audience member seated a few rows from the stage told the Las Vegas Weekly that the show momentarily continued on Saturday night before the music stopped and screams and groans could be heard coming from the pit.
One audience member reportedly tweeted that the "wire snapped" and the performer "fell fast & awkwardly at least 50 feet".
Another witness told The Las Vegas Sun:
"Initially, a lot of people in the audience thought it was part of the [show]. But you could hear screaming, then groaning, and we could hear a female artist crying from the stage."
Cirque du Soleil founder Guy Laliberte reportedly said in a statement:
"The entire Cirque du Soleil family is deeply saddened by the accidental death of Sarah [Sassoon] Guyard, artist on the production 'Ka,' that happened on Saturday, June 29, in Las Vegas... Our thoughts are with her family and the entire Cirque du Soleil family."
Sassoon was with the original cast of Ka since 2006. She was a graduate of Anne Fratellini Art & Circus Academy, named for the famed French circus clown and actress.
The official website for Cirqeufit, where Guillot served as a coach, said she was an acrobatic and aerialist specialist.