A man has been arrested outside Buckingham Palace after suspected shotgun cartridges were thrown into the Palace grounds on Tuesday night.
Police swooped and arrested a man outside the Palace about 7pm.
Officers said a man approached the palace gates and threw a number of items, including suspected shotgun cartridges, into the grounds.
A controlled detonation was carried out. No shots were fired, Scotland Yard said, and the incident is not being treated as terror related.
Neither the King nor the Queen Consort were at Buckingham Palace at the time of the man’s arrest.
Met Chief Superintendent Joseph McDonald said: “Officers worked immediately to detain the man and he has been taken into police custody.
“There have been no reports of any shots fired, or any injuries to officers or members of the public.
“Officers remain at the scene and further enquiries are ongoing.”
The suspected cartridges have been removed and taken for examination. The man was arrested on suspicion of possession of an offensive weapon.
Cordons were put in place after the man was also found to be in possession of a suspicious bag, said police.
Roads later reopened and the majority of cordons were lifted by 9pm.
Buckingham Palace declined to comment and said the incident was a matter for the Metropolitan Police.
The incident comes four days before King Charles’ historic coronation on May 6.
King Charles and Queen Consort Camilla will be crowned in Westminster Abbey in front of 2,200 guests, including other members of the royal family and world leaders.
There will be extensive security in the capital for the coronation.
Policing minister Chris Philp has described it as a “huge policing operation", as heads of state and foreign royals from around the world travel to the UK.