Concern prevails in Britain after Queen Elizabeth's health condition was announced and placed under surveillance

Buckingham Palace announced, in a statement, Thursday, that Queen Elizabeth II's doctors were "concerned" about her health, and recommended that she "remain under medical supervision."

In a statement, the palace said the 96-year-old was "resting at Balmoral Castle" in Scotland. A source in the royal palace told CNN that the Queen's family had been informed of her health condition.

Kensington Palace announced that Prince Charles, the Queen's son, and Prince William, her grandson, had traveled to Queen Elizabeth after news of her health.

The Queen met the new British Prime Minister, Liz Terrace, on Tuesday. "The entire country is deeply concerned by the news from Buckingham Palace," she wrote on her Twitter account, Thursday. "My thoughts - and those of people across the UK - are with Her Majesty and her family at this time," she added.