London’s Metropolitan Police arrested a man outside Buckingham Palace on Tuesday after he allegedly threw suspected shotgun cartridges into the palace grounds, just days before the coronation of King Charles III.

Police attended the palace about 7pm local time and arrested the man on suspicion of possessing an offensive weapon. He also had suspicious bag that was destroyed in a controlled explosion, police said in a statement.

“There have been no reports of any shots fired, or any injuries to officers or members of the public,” Chief Superintendent Joseph McDonald said in the statement.

The items the man allegedly threw into the palace ground are being analyzed, the statement added.

Neither King Charles nor Queen Camilla were at Buckingham Palace during Tuesday’s incident.

Police and security services are preparing for the coronation of King Charles on Saturday, attended by heads of state and global dignitaries.