It was a heartbreaking Sunday service for former U.S. president Jimmy Carter last Dec. 20 when he opened up about the tragic loss of his 28-year-old grandson Jeremy Carter.

Carter, 91, shared this personal revelation during his regular Sunday school lecture at Maranatha Baptist Church in Plains, Georgia, according to NBC News. He first apologised to his congregation for being late, then proceeded to share about the loss his family endured the day before.

Carter explained that Jeremy was not feeling well that day, but they were caught off guard when he slipped out of consciousness. "When he got ready to eat supper he told his mother that he thought he'd go lie down awhile," he said. "His heart quit beating."

His mother immediately called 911, and the operator even told her how to do CPR to help bring Jeremy back to life. An ambulance later rushed the young man to the hospital where he was revived. But just a moment after Carter arrived at the hospital at around 1:30 a.m., "his heart stopped beating again," he shared. He said they still haven't found out yet the cause of Jeremy's death.

The 39th president of the U.S. lovingly recalled his grandson during the sermon as "a wonderful young man" and "a very special child." Even as a young boy, Carter said Jeremy was always thinking about others.

"Papa, are you going to die someday?" Carter recalled Jeremy asking him when he was still a child. "And I was really happy that my grandchild was concerned about me."

This piece of tragic news came just two weeks after Carter made the announcement that the cancer cells in his brain have disappeared. "Went for an MRI this past week and they (doctors) didn't find any cancer at all in the brain," Carter happily said on Dec. 6.