Former U.S. President Jimmy Carter announced on Sunday that his 28-year-old grandson died from a sudden heart attack.

Carter made the announcement just hours after his death while he was teaching a Sunday school class at Maranatha Baptist Church in Plains, Georgia.

"When he got ready to eat supper, he told his mother that he thought he would lie down awhile," Carter said about his grandson, Jeremy Carter, NBC News reports. "His heart quit beating."

The former leader also described his grandson as "a very special child" and "a wonderful young man whom we loved very much."

Despite his tragic loss, the 91-year-old leader urged the congregation to "be filled with a sense of joy and thanksgiving," The Atlanta Journal-Constitution reports.

"I should be joyful and thankful to God for giving me both life and freedom," he added.

According to Maranatha Baptist Church Rev. Jeremy Shoulta, Jeremy had not been feeling well and decided to take a nap on Saturday. That's when his heart stopped and his mother performed CPR before paramedics arrived to transport him to a hospital.

"They were trying to keep his heart going and eventually, later in the night or the wee hours of (Sunday) morning, his heart stopped," Shoulta told CNN.

Jeremy's brother Josh also shared an emotional blog post explaining the rapid decline of Jeremy's health. Josh said that Jeremy "couldn't eat well and his legs ached. He had nearly every doctor at Emory look at him, he wrote. "They ended up prescribing him Vitamin A and Vitamin D. After all that. He got the full work over and really just needed vitamins," Josh says.

He also said that Jeremy had underwent "a whole battery of tests" two weeks ago.

"I find out later that he had a heart attack at home while alone in the kitchen with our mom," he wrote.

Earlier this month, the ex-president announced that he is virtually cancer free just four months after starting treatment for an aggressive form of brain cancer.