Kaiser Permanente CEO Bernard Tyson dies at 60

Kaiser Permanente CEO Bernard Tyson died unexpectedly Sunday, the health system said.

Tyson, 60, who has served as the head of Kaiser Permanente since 2013, died in his sleep, the health system confirmed, though the cause of death was not released.

He leaves behind a legacy as an "outstanding leader, visionary and champion for high-quality, affordable health care for all Americans," Kaiser Permanente said.

Gregory A. Adams, Kaiser Permanente executive vice president and group president, has been named interim CEO by the health system's board.

"Bernard was an exceptional colleague, a passionate leader, and an honorable man. We will greatly miss him," said board member Edward Pei, chair of the Executive Committee and the Governance, Accountability and Nominating Committee. "The board has full confidence in Greg Adams' ability to lead Kaiser Permanente through this unexpected transition."

This is a developing story.