Police used a taser gun on a man seen pointing a knife at his own throat outside the British prime minister's Downing Street residence, police said on Monday.
The 42-year-old man, who had been shouting in the street, failed to respond when challenged by police shortly before 9pm on Sunday, and was then hit with the electric weapon.
He suffered a minor head injury when he fell and was taken to hospital as a precaution.
He was later arrested on suspicion of possession of a knife and affray, and remained in custody Monday.
The prime minister's apartment and office is at 10 Downing Street, a road now sealed off by high gates at both ends.
The incident came exactly a month to the day since police used a Taser on a man brandishing knives outside Buckingham Palace, the sovereign's official residence.
Talhat Rehman, 54, was charged with affray and possessing a bladed weapon in public.
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