Police said a controlled explosion was staged and a man was arrested outside Buckingham Palace after hurling cartridges of suspected shotguns onto the palace grounds.

Scotland Yard said a fence was set up after the man was taken into custody at around 19:00 BST on Tuesday after approaching the palace gates.

He was arrested on suspicion of possessing an offensive weapon.

There were no reports of shootings or injuries to officers or the public.

Police said they did not consider the incident to be terrorism-related.

It is understood that it is being treated as an isolated mental health incident.

Police later said the man was searched and a knife was found, but he was not carrying a gun.

The arrest comes just four days before the King’s coronation – an event that will be attended by world leaders and other royals from around the world.

The Metropolitan Police said the man was also found in possession of a suspicious bag.

A controlled explosion was carried out as a precautionary measure after evaluation from experts.

The King and Queen were not at Buckingham Palace at the time of their arrest.

Police Chief Joseph McDonald said: “Officers worked immediately to apprehend the man and he was in police custody.

“There have been no reports of any shootings, or any injuries to officers or members of the public.

“Officers remain at the scene and further investigations are ongoing.”

BBC royal producer Sarah Parrish was in the broadcast area outside Buckingham Palace when she was asked to leave and wait outside.

She told BBC News Channel that those being evacuated “heard a controlled explosion and then we were allowed to return.”

The suspected pistol cartridges have been recalled and will be examined by experts.

Roads have now reopened and barriers have been removed.

Buckingham Palace declined to comment.

A round of steel is scheduled to take place in the capital for the Coronation at Westminster Abbey on Saturday.

Police Minister Chris Philp described it as a “huge policing operation”.