Britain’s royal family on Thursday rushed to be with Queen Elizabeth II after doctors said they were concerned about the health of the 96-year-old monarch and that said she should remain under medical supervision.

“Following further evaluation this morning, the Queen’s doctors are concerned for her Majesty’s health and have recommended she remain under medical supervision,” Buckingham Palace said in a statement. “The Queen remains comfortable and at Balmoral [Castle].”

Following the statement, the queen’s immediate family members were seen arriving at the Balmoral Castle in Scotland.

Among those present were the queen’s eldest son and heir to the throne Prince Charles and his wife Camilla, and her grandson, Prince William, the Duke of Cambridge, according to The Guardian. Her other children – Anne, Andrew and Edward – were also at the castle.

Harry and Meghan, the Duke and Duchess of Sussex, who are in Britain for a number of events, would also travel to Scotland, a spokesperson of the couple said, The New York Times reported.

Elizabeth is Britain’s longest-reigning sovereign and the world’s oldest monarch. She has been suffering from what Buckingham Palace has called “episodic mobility problems” since the end of last year.

On Thursday, British Prime Minister Liz Truss said that the whole country is deeply concerned by the news from Buckingham Palace about the queen’s health.

“My thoughts – and the thoughts of people across our United Kingdom – are with Her Majesty The Queen and her family at this time,” the prime minister wrote on Twitter.

Truss, who took over as the new prime minister of the United Kingdom on September 6, had herself travelled to Balmoral to be appointed to the post by the queen on Wednesday.

This was the first time during the queen’s reign that the handing over of power took place at her summer retreat at Aberdeenshire instead of Buckingham Palace.

Justin Welby, the archbishop of Canterbury and leader of the Church of England, said the prayers of the nation are with the queen.

Canadian Prime Minister Justin Trudeau extended his wishes to the queen and the royal family. “My thoughts, and the thoughts of Canadians across the country, are with her Majesty Queen Elizabeth II at this time,” he said in a tweet. “We are wishing her well, and sending our best to the Royal Family.”

United Nations Secretary-General Antonio Guterres also said his thoughts are with the queen, her family and the people of the United Kingdom at this time.