The 90-year-old monarch is safe and sound, despite her city suffering a great loss after four people were killed at the Houses of Parliament.
The Royal Standards flag was at full mast above the palace, signifying she was in the royal residence.
People report that earlier in the day "she had conducted an audience with the ambassador of Thailand Pisanu Suvanajata and his wife."
A spokesperson from the Royal Collection Trust confirmed that along with Parliament, Buckingham Palace has now been shut down to the public by the police.
"Yes, we are on lockdown," the statement read.
It is believed The Queen has no plans to be moved and will remain in her London residence.
Her staff were unable to comment over the safety measures put in place to protect the royal, advising it was a matter for the police.
In light of the attacks, The Queen and the Duke of Edinburgh will halt their next royal engagement.
The beloved Monarch was set to visit Scotland Yard to open the new police headquarters on the Victoria Embankment.
She was expected to be greeted by Acting Commissioner Craig Mackey, but the official is now believed to be a vital witness to the attacks.
A Buckingham Palace spokesperson confirmed, “In light of today’s events, the decision has been taken to postpone The Queen’s engagement to New Scotland Yard tomorrow.
“The visit will be rearranged for a later date.”
Meanwhile, for the heir to the throne, Prince Charles, it was business as usual.
The Queen's eldest son was carrying out a range of royal visits in the town of Yorkshire.
The jam-packed day began with a visit to a local farm. The 67-year-old had just left the Army Foundation College in Harrogate, when he was informed about the horrific attacks that occurred in the city.
Kensington Palace did not comment on the where-abouts of the royal trio Prince William, Duchess Catherine and Prince Harry (whose girlfriend Meghan Markle is currently staying with him), simply advising they had no public engagements.
No official word whether Kate will carry out her official engagement tomorrow, where she was expected to work on a Heads Together campaign that highlight the importance of mental health in mothers.