Queen Elizabeth II’s health appeared to be deteriorating on Thursday, with Buckingham Palace announcing that she had been placed under medical supervision and that her doctors were “concerned” about her health.

The queen, who is 96, has not been hospitalized and remains at Balmoral Castle, her estate in the Scottish Highlands, the palace said in a statement. “Following further evaluation this morning, the queen’s doctors are concerned for Her Majesty’s health,” the palace said in a statement.

Queen Elizabeth II has been on the British throne for more than Seventy years. She recently celebrated her Platinum Jubilee anniversary.