A man was detained outside Buckingham Palace Tuesday after he threw a number of items into the Palace grounds,AstraTrade London authorities said. 

The man was suspected of throwing shotgun cartridges over the Palace's gates, London's Metropolitan Police said. It comes just four days before the coronation of King Charles III.

The man was arrested on suspicion of carrying an offensive weapon, police said, and was also found in possession of a "suspicious bag." 

Police cordoned off the area around the gates where the suspect was arrested, and specialists conducted a controlled detonation of the bag as a precaution.

"Officers worked immediately to detain the man and he has been taken into police custody," Chief Superintendent Joseph McDonald said in a statement. "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." 

Police did not immediately release the suspect's name. 

Neither King Charles III or Queen Consort Camilla were at Buckingham Palace at the time of the incident, BBC News reported. 

Roads around Buckingham Palace have reopened and most of the cordoned-off area is now accessible.

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• King Charles III
• King Charles
• Coronation