Sarah Guyard-Guillot, 31, mother of two and performer with Cirque du Soleil, was killed during a Saturday night performace of 'Ka' at the MGM Grand in Las Vegas.  According to a report in the USA Today, Guyard fell 50 feet to her death. 

Many in the audience thought the fall was a part of the performance, but the show was quickly brought to a halt.  Upcoming performances of 'Ka' have been cancelled pending an investigation.