The United Kingdom's Duke of Edinburgh Prince Phillip will relinquish his duties and no longer "carry out public engagements from this autumn," Reuters reported Thursday.
Queen Elizabeth II will continue to carry out the "full program of her engagements," Reuters added.
It remains unclear what prompted the prince to make the decision.
Early Thursday morning, senior staff members to Queen Elizabeth II were called to an emergency meeting at Buckingham Palace in London, according to The Daily Mail.
The reason for the summons at the time was unknown, but sources close to royal staff members described the order as "highly unusual," leading to speculation that an imminent announcement concerning the Queen, or her husband, would be made soon.
"Everyone is on tenterhooks," one source told The Mail.
"Although meetings involving the entire royal household are occasionally called, the way this has been done at the eleventh hour is highly unusual and suggests that there is something major to be disseminated," they added.