Habitat for Humanity co-founder Millard Fuller has died. He was 74.

Fuller’s wife, Linda, says Fuller died about 3 a.m. Tuesday at a Georgia hospital, but she says the cause of death is unknown.

Linda Fuller says her husband had complained of chest pains, headache and that his throat was tightening up. She says she took him to an emergency room.

Former President Jimmy Carter issued a statement calling Fuller “one of the most extraordinary people I have ever known.”

After running Habitat with his wife for nearly three decades, Fuller lost control of the charity in a conflict with the organization’s board.