Prince William and Kate appeared shocked after learning of Nelson Mandela's death at the royal premiere of Mandela: Long Walk To Freedom in London.
Mandela's daughters Zindi and Zenani left the cinema shortly before they were about to watch the film about their father's life.
Stopping the screening of the movie was discussed, but Mandela's daughters asked that the film continue, a spokesman with the production said. Earlier they had smiled and posed for photographs on the red carpet and enjoyed an animated conversation with the Duke and Duchess of Cambridge.
The Daily Mail reported the royal couple were informed discreetly by an aide toward the end of the film.
The rest of audience were told after the movie when producer Anant Singh got up on stage to announce the "sad news".
Prince William's tribute to Mandela:
The film starring Idris Elba chronicles Mandela's life from childhood to his inauguration as the first democratically elected president of South Africa.
At its opening last week it became the hghest grossing picture in South Africa.