Was watching their updates yesterday.  Saw this today:

We regret to announce that during the attempt of the Mont Blanc crossing by Kilian and Stéphane Brosse this morning, Stéphane lost his life in an unfortunate accident. In these difficult times, Kilian is well physically and is devoting all his energies to support the family and friends. In the upcoming days he will issue an official statement. Thank you for your understanding and support. Kilian team.

http://www.summitsofmylife.com/en/team

The pictures yesterday looked like some unbelievably challenging climbing.