According to Martin O'Donnell, Halo and Destiny composer, he is no longer for Bungie and was fired "without cause". This is per a tweet he sent this morning.
Community Manager David Dague had this to say about O'Donnell:
"For more than a decade, Marty O'Donnell filled our worlds with unforgettable sounds and soundtracks, and left an indelible mark on our fans. Today, as friends, we say goodbye. We know that wherever his journey takes him, he will always have a bright and hopeful future. We wish him luck in all his future endeavors."
I'll keep you posted with any news, and truly believe we all with Marty the best of luck. His music was a huge part of my childhood.