An aircraft carrying members of the Royal Family has landed in Aberdeen, Scotland.
Per BBC News, those on board included the Duke of Cambridge, the Duke of York and the Earl and Countess of Wessex - all of whom are now believed to be making their way to Balmoral to be with the Queen. The journey is roughly 40 miles.
The plane arrived at Aberdeen Airport just before 4:00PM BST.
Their arrival comes just hours after Buckingham Palace shared the following announcement shortly after midday on Thursday, September 8:
"Following further evaluation this morning, The Queen’s doctors are concerned for Her Majesty’s health and have recommended she remain under medical supervision.
"The Queen remains comfortable and at Balmoral."
Prince William was seen without his wife, the Duchess of Cambridge, at his side. She will reportedly be staying in Windsor with the couple's children, who have recently returned to school.
A representative for Prince Harry has confirmed that he is also traveling to Balmoral to be with the Queen. The Duke of Sussex was in Germany earlier in the week and was due to appear at a charity event in London this evening.
Megan Markle will be staying in London and "may travel to Balmoral at a later date".
Prince Charles, the Duchess of Cornwall, and Princess Anne are all reportedly at Balmoral with Her Majesty, as of this writing.
On Tuesday, Her Majesty appointed Liz Truss as the United Kingdom's new prime minister after the latter won the summer Conservative leadership bid.
The occasion took place at Balmoral, as the Queen did not travel to London for the event, which has often taken place at Buckingham Palace for previous prime ministers.
In response to today's news, the new PM tweeted that the country should be "deeply concerned" about the Queen's wellbeing.
"The whole country will be deeply concerned by the news from Buckingham Palace this lunchtime," Truss tweeted. "My thoughts - and the thoughts of people across our United Kingdom - are with Her Majesty The Queen and her family at this time."
Additionally, Labour leader Sir Keir Starmer also shared his concerns about the news, tweeting: "Along with the rest of the country, I am deeply worried by the news from Buckingham Palace this afternoon.
"My thoughts are with Her Majesty The Queen and her family at this time, and I join everyone across the United Kingdom in hoping for her recovery."
A statement from former PM Tony Blair reads: "It is deeply concerning to hear today's news from Buckingham Palace. My thoughts and prayers are with Her Majesty the Queen and her family at this worrying time."
Back in June, Queen Elizabeth II celebrated her Platinum Jubilee, with the entire nation enjoying a long weekend of celebrations to mark Her Majesty's 70-year record reign.