Queen Elizabeth’s committal service is underway at St. George's Chapel at Windsor Castle.

Guests at the service include United Kingdom Prime Minister Liz Truss and former Prime Minister Tony Blair.

At the end of the service, Queen Elizabeth’s coffin will be lowered into the royal vault.

Queen Elizabeth’s coffin has arrived at St. George's Chapel in Windsor for the final ceremony of the week, a committal service. Elizabeth will be reunited with her husband, Prince Philip, and her coffin will be lowered into the royal vault.

The hearse is draped with flowers thrown by onlookers.

Rev. Dr. Iain Greenshields, moderator of the General Assembly of the Church of Scotland, recounted to ABC News the weekend he spent with Queen Elizabeth in Balmoral in her final days.

“She was 96 and you could see her fragility, but as soon as she started talking and as soon as she was engaged with you, a different kind of person emerged,” Greenshields said.

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Reverend speaks about recent, final meal with Queen Elizabeth II

Rev. Dr. Iain Greenshields detailed the warmth and humor the queen still possessed just days before she died.

She was still filled with her signature humor, he noted.

“I was staying in a place called the Tower Rooms and she said, ‘Your queen is sending you to the tower. She just smiled at me as she said that, and she made sure that I understood, that I got the joke,” he said.

“I asked her what I could possibly give to somebody who has everything, and she smiled at me. I offered her the cross, and she took it very graciously and she wished me the very best in my year ahead as the moderator of the Church of Scotland,” he said.

For Queen Elizabeth, faith was “fundamental,” he said.

“She said right at the beginning of her time, when she was becoming queen, that she was going to ask God for wisdom,” he said, “and that’s something that persisted throughout her life.”

“When I was chatting to her about her faith, she spoke about it and said she had no regrets about starting that journey of faith. She had no regrets at all,” Greenshields said.

Greenshields called her death “astonishing,” noting that she’d been “so vital, so alive, so engaging.”

President Joe Biden and first lady Jill Biden are aboard Air Force One heading home to the United States after attending Queen Elizabeth’s funeral.

Former President Barack Obama posted a video to Twitter remembering his first time meeting the queen.

"She reminded me very much of my grandmother, which surprised me, not just in appearance but also in manner. Very gracious, and also no nonsense. Wry sense of humor that she could not have been more kind or thoughtful to me and Michelle," Obama recalled.

"Shortly thereafter, Michelle and Malia and Sasha, my two daughters, had occasion to go back to England. Buckingham Palace reached out and Her Majesty had invited Michelle, and the two girls to tea," he said. "She had then offered the girls to drive in her golden carriage around the grounds of Buckingham Palace. It was the sort of generosity and consideration that left a mark in my daughters' lives."

He added, "The combination of a sense of duty, and a clear understanding of her role as a symbol for a nation and as the carrier of a certain set of values, combined with a very human quality of kindness and consideration. I think that's what made her so beloved, not just in Great Britain but around the world."

Michelle Obama on Monday recounted her first memory with the queen in a video on Instagram, and wrote, “My heart goes out to the Royal Family and all those mourning Her Majesty Queen Elizabeth II's passing.”