A man armed with a knife has been arrested outside Buckingham Palace, leaving two police officers injured, Scotland Yard has confirmed.
The suspect is being held on suspicion of grievous bodily harm and assault on police after being stopped in possession of the weapon at around 8.35pm on The Mall.
As he was detained, two male officers suffered "minor injuries" to their arms, the Metropolitan Police said.
The London Ambulance Service attended to treat the injured men but they were not taken to hospital.
No other people were injured.
Images posted online showed a heavy police presence outside the palace, with emergency vehicles packing out the road.
Armed police were reported to be among those responding to the alleged attack.
Twitter user Amir Jan Malik wrote: "Stuck outside Buckingham palace with many armed police officers. Heavy rifles on display traffic at a halt."