Buckingham Palace announced that after 70 years on the throne, Queen Elizabeth II died at the age of 96. Her death Thursday came just hours after the Palace announced that she was under medical supervision, with medical officials concerned about her health. Members of the royal family had rushed to her side after her health took a turn for the worse.

“The Queen died peacefully at Balmoral this afternoon,” the palace said in a statement. “The King and The Queen Consort will remain at Balmoral this evening and will return to London tomorrow.”

The queen was Britain’s longest-reigning monarch. With her death, her 73-year-old son Charles automatically becomes monarch, though the coronation might not take place for months. While it is not officially known whether he will choose to call himself King Charles III or some other name, during a speech shortly after the announcement of the Queen’s death, British Prime Minister Liz Truss referred to him as King Charles III.

“The death of my beloved mother, Her Majesty The Queen, is a moment of the greatest sadness for me and all members of my family,” Charles said in a statement. “I know her loss will be deeply felt throughout the country, the Realms and the Commonwealth, and by countless people around the world.

The Associated Press contributed to this report.