Buckingham Palace is currently in lockdown after a ‘sword attack’ on police officers.
Unconfirmed reports state the man had a sword, however police officers said a man was stopped outside the Royal grounds in possession of a knife at around 8.35pm. He was arrested at the top of the Mall, close to the palace gates after injuring two officers.
The Queen, who is believed to currently be holidaying with other members of the royal family, was not at her London residence at the time of the attack.
A statement by the London Metropolitan Police on Twitter said: "Two police officers suffered minor injuries during the course of detaining the man".
The attack, the motivations of which are not known, comes only about an hour after another knife attack in a European capital, Belgium, where a man attacked two soldiers with a knife.
"The London Ambulance Service were called and they were treated at the scene. They have not been taken to hospital.
"No others persons have been reported injured. Officers remain on scene and enquiries are ongoing."
One eyewitness told the BBC:
"I was walking toward The Mall and St James's Park when I saw police rush down toward the palace in great numbers.
"As we got further down The Mall we saw armed police outside a police van, at which point we were able to walk closer to the palace still, where we were eventually stopped by a cordon.
"All we were told was that there's been an incident.
"A few minutes later police came by to have us clear the area and move further away from the palace."