Crowds are gathering outside Queen Elizabeth II's Buckingham Palace residence in London on Thursday, as concerns about the health of the 96-year-old Queen grows.

As many as 100 people braved torrential rain to stand at the palace gates, according to AFP, as senior royals rushed to Balmoral in Scotland, where the Queen is being treated. 

Royals arrive at Queen's Balmoral residence

AFP journalists witnessed royal family members, including Prince William, arrive Thursday afternoon at Queen Elizabeth II's Balmoral residence in Scotland after her health deteriorated.

Prince William, the Queen's grandson and second in line to the throne, as well as the monarch's middle son Prince Andrew and her youngest son Prince Edward, arrived at the castle in a car.

The Queen's heir Prince Charles and his sister, Princess Anne, were already at the residence.

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Reactions from politicians and officials

Britain's royal family rushed to be with Queen Elizabeth after doctors said on Thursday they were concerned about her health and that she should remain under medical supervision. 

Here is some reaction to the news:

British Prime Minister Liz Truss 

"The whole country will be deeply concerned by the news from Buckingham Palace this lunchtime. My thoughts - and the thoughts of people across our United Kingdom - are with Her Majesty The Queen and her family at this time."

Opposition labor leader Keir Starmer 

"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."

Leader of opposition liberal democrats Ed Davey

"The whole nation’s thoughts and prayers are with Her Majesty The Queen and her family as we all hope and pray for her full recovery."

First minister of Scotland Nicola Sturgeon 

"All of us are feeling profoundly concerned at reports of Her Majesty’s health. My thoughts and wishes are with the Queen and all of the Royal Family at this time."

First Minister of Wales Mark Drakeford 

"Concerned to hear the news from Buckingham Palace. I send my best wishes to Her Majesty and her family on behalf of the people of Wales."

Archbishop of Canterbury Justin Welby 

"My prayers, and the prayers of people across the @churchofengland and the nation, are with Her Majesty The Queen today. May God’s presence strengthen and comfort Her Majesty, her family, and those who are caring for her at Balmoral."

President of Catholic Bishops' conference of England and Wales, Cardinal Vincent Nichols

"I am concerned to hear the news about the Her Majesty The Queen's health. I offer my prayers for her and her family. May the blessings of the Lord strengthen and comfort her and her family."

Speaker of Parliament Lindsay Hoyle 

"I know I speak on behalf of the entire House when I say we send all the best wishes to Her Majesty The Queen."

UN Spokesperson Stephane Dijjarric 

UN Secretary-General Antonio Guterres' "thoughts are with the Queen, her family and the people of the United Kingdom at this time."

Prime Minister of Canada Justin Trudeau

"My thoughts, and the thoughts of Canadians across the country, are with Her Majesty Queen Elizabeth II at this time. We’re wishing her well, and sending our best to the Royal Family."

Australia's Governor-general David Hurley 

"Following news from Buckingham Palace, and on behalf of all Australians, the Governor-General and Mrs. Hurley’s thoughts and prayers are with Her Majesty The Queen and the Royal family at this time."

White House spokesperson John Kirby after President Joe Biden briefed on situation 

"His and the first lady's thoughts are solidly and squarely with the queen today and her family."

US Senate Republican leader Mitch Mcconnell 

"The queen is an exemplar of steady leadership and a beloved figure around the world. She has been a historic friend of the United States. The decades of her reign have seen a profound deepening of the special relationship between our two countries that has literally changed the world. The queen, the royal family, and all our friends in the United Kingdom have our thoughts and our prayers."

US ambassador to United Kingdom Jane Hartley 

“I join the people of the United Kingdom, the United States, and across the world in sending our thoughts and prayers to Her Majesty The Queen and her family.”

Commonwealth Secretary-General Patricia Scotland 

"Like everyone, I am deeply concerned to hear the statement from Buckingham Palace today. On behalf of every nation and citizen of the Commonwealth family, I send my best wishes to Her Majesty and the Royal Family. She will remain in my prayers."

EU Commission President Ursula Von Der Leyen 

"My thoughts and prayers are with her. She represents the whole history of Europe that is our common home with our British friends, she has always given us stability and confidence, she has shown an immense amount of courage, and is a legend in my eyes."

Former Prime Minister Tony Blair, via his institute 

"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."

Former Prime Minister David Cameron 

"Deeply concerned by the news this afternoon from Buckingham Palace. I send my heartfelt thoughts and prayers to Her Majesty The Queen and the Royal Family at this worrying time."