Dr. Paul Farmer, an American medical anthropologist and physician who was known for bringing health care to some of the world’s poorest countries, died Monday at the age of 62, his nonprofit group Partners in Health said.

Farmer “unexpectedly passed away today in his sleep while in Rwanda,” Partners in Health said in a statement.

Farmer co-founded Partners in Health, an international nonprofit organization, in 1987 with a mission to provide modern health care to those in some of the poorest and sickest communities. It currently works in 12 countries, according to the organization.

In a statement following his death, Partners In Health CEO Dr. Sheila Davis said Farmer’s “vision for the world will live on through” the organization.

“Paul taught all those around him the power of accompaniment, love for one another, and solidarity. Our deepest sympathies are with his wife Didi and three children,” she said.

The launch of Partners In Health followed Farmer moving to Haiti after graduating from college in 1982 and living among the country’s poorest farmers while helping set up a new medical infrastructure, according to The New York Times.

He later returned to the U.S. where he attended Harvard Medical School, an institute that would years later recognize him as its first incumbent to the Kolokotrones University Professorship for his medical work in underserved and remote areas. He was also appointed chair of the Department of Global Health and Social Medicine at Harvard Medical School and chief of the Division of Global Health Equity at Brigham and Women’s Hospital.

In addition to his high academic distinctions and appointments, he was the subject of the 2017 documentary film “Bending the Arc,” which documented his efforts to expand global health care with his fellow Partners in Health co-founders Dr. Jim Yong Kim and activist Ophelia Dahl. He was also the subject of the 2003 Pulitzer Prize-winning book, “Mountains Beyond Mountains: The Quest of Dr. Paul Farmer, a Man Who Would Cure the World.”

Among those expressing their condolences Monday were former President Bill Clinton, former Secretary of State Hillary Clinton, and their daughter Chelsea Clinton, who lauded Farmer as “one of the most extraordinary people we have ever known.”

“His pioneering work with Partners In Health touched millions of lives, advanced global health equity, and fundamentally changed the way health care is delivered in the most impoverished places on Earth. He was brilliant, passionate, kind, and humble. He saw every day as a new opportunity to teach, learn, give, and serve—and it was impossible to spend any amount of time with him and not feel the same,” the family said.

Rwanda’s president, Paul Kagame, also expressed his condolences following news of Farmer’s death, tweeting that the philanthropist “combined many things hard to find in one person.”

“The weight of his loss is in many ways personal, to the country of Rwanda (which he loved and to which he contributed so much during its reconstruction), to my family and to myself. I know there are many who feel this way in Africa and beyond,” he wrote.