As Prince William mourned Prince Philip’s death, the Duke of Cambridge and his wife Kate Middleton were determined to break the news to their children in a gentle way.

The 38-year-old’s grandfather died on Friday at age 99.

William and the Duchess of Cambridge, 39, share three children: Prince George, 7, Princess Charlotte, 5, and Prince Louis, 2.

"William told George, Charlotte and Louis that Prince Philip has ‘gone to heaven’ and ‘is an angel now,’" a royal insider told Us Weekly on Tuesday.

"They’re still so young so he and Kate wanted to let them down gently," added the palace source.

PRINCE PHILIP'S FINAL HOURS WERE 'PEACEFUL' AND 'GENTLE' SOPHIE, COUNTESS OF WESSEX SAYS

Prince Philip, Duke of Edinburgh, Catherine, Duchess of Cambridge, Princess Charlotte of Cambridge, Prince George of Cambridge and Prince William, Duke of Cambridge look on from the balcony during the annual Trooping The Colour parade at the Mall on June 17, 2017, in London, England.  (Photo by Karwai Tang/WireImage/Getty )

On Monday, William took to social media where he shared a moving statement paying tribute to the Duke of Edinburgh.

"My grandfather's century of life was defined by service – to his country and Commonwealth, to his wife and Queen, and to our family," the statement began.

William continued: "I feel lucky to have not just had his example to guide me, but his enduring presence well into my own adult life – both through good times and the hardest days. I will always be grateful that my wife had so many years to get to know my grandfather and for the kindness he showed her. I will never take for granted the special memories my children will always have of their great-grandpa coming to collect them in his carriage and seeing for themselves his infectious sense of adventure as well as his mischievous sense of humour!"

"My grandfather was an extraordinary man and part of an extraordinary generation. Catherine and I will continue to do what he would have wanted and will support The Queen in the years ahead. I will miss my Grandpa, but I know he would want us to get on with the job," it concluded. 

PRINCE HARRY ARRIVES IN UK AHEAD OF GRANDFATHER PRINCE PHILIP'S FUNERAL

Prince William's grandfather Prince Philip passed away on Friday at age 99. (AP Photo/Alastair Grant)

The statement included a photo from 2015 of Philip sitting next to William and Middleton's eldest son, George, while in a carriage.

Back in 2017, William told The Calm Zone how important it was for his children to feel comfortable expressing their feelings to the duke and duchess.

"Catherine and I are clear that we want both George and Charlotte to grow up feeling able to talk about their emotions and feelings," he explained at the time. "Over the past year we have visited a number of schools together where we have been amazed listening to children talk about some quite difficult subjects in a really clear and emotionally articulate way – something most adults would struggle with."

"Seeing this has really given me hope that things are changing and that there is a generation coming up who find it normal to talk openly about their emotions," he shared. Emotional intelligence is key for us all to deal with the complexities of life and relationships."

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Britain's Prince William leaves a Service of Thanksgiving for the life and work of Lord Snowdon at Westminster Abbey in London, Britain, April 7, 2017. REUTERS/Hannah McKay - RTX34JXQ

Prince William is the eldest son of Prince Charles and the late Princess Diana. (REUTERS)

Philip is survived by his wife, Queen Elizabeth II, and their four children – Prince Charles, Princess Anne, Prince Andrew and Prince Edward – as well as eight grandchildren and 10 great-grandchildren.

The Associated Press contributed to this report.