As the letter was being received, tourists and guests were still visiting Holyroodhouse. Roads around Holyroodhouse were closed off this morning, with ambulances and fire trucks sitting outside.
This is the second instance of such a letter being sent to a notable location in Edinburgh. Last month, another letter with similar white powder was sent to Scottish National Party headquarters (the party of Scotland’s First Minister Nicole Sturgeon), a close neighbor of Holyroodhouse.
A royal spokesperson confirmed the monarch was not at Holyroodhouse when the letter was received. She is at her London home, Buckingham Palace.
This article originally appeared on PEOPLE.