This is heartbreaking. In the new BBC documentary Diana, 7 Days, Prince William and Prince Harry candidly opened up about Princess Diana‘s tragic passing — and recalled the moment they learned their mom had died. “One of the hardest things for a parent to have to do is to tell your children that your other parent has died. How you deal with that, I don’t know,” Harry, 32, said of his father, Prince Charles, breaking the news of Diana’s death to his two sons back in August 1997.

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“[Our dad] was there for us — he was the one out of two left, and he tried to do his best and to make sure that we were protected and looked after. But he was going through the same grieving process as well,” Harry continued. Watch the video below for William and Harry’s reactions to learning their mother had passed away.

“At the time, my grandmother Queen Elizabeth wanted to protect her two grandsons and my father as well. Our grandmother deliberately removed the newspapers and things like that so there was nothing in the house to read,” William, 35, said. “We didn’t know what was going on. Back then there were no smart phones and things like that, so you couldn’t get your news. Thankfully, we had the privacy to mourn and to try to collect our thoughts and have that space away from everybody. We had no idea the reaction to her death would be quite so huge.”

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At the time of Diana’s passing, William was just 15 years old and his brother Harry was 12. The boys were on vacation with their father and grandparents at the royal family’s Balmoral Estate in Scotland. After Diana’s passing was announced to the world, Queen Elizabeth received backlash for keeping her young grandsons in Scotland instead of bringing them back to London.

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“All of us were in new territory. My grandmother and my father believed we were better served in Balmoral, having the walks and space and the peace to be with the family and not be immersed or having to deal with serious decision or worries straightaway,” William explained.