"We believe we are experiencing a new trend in the threat we face, as terrorism breeds terrorism, and perpetrators are inspired to attack not only on the basis of carefully constructed plots after years of planning and training - and not even as lone attackers radicalized online - but by copying one another and often using the crudest means of attack", she said. "One whole day", she said.
He had appeared in a documentary, "The Jihadis Next Door", that aired on British television a year ago.
London Mayor Sadiq Khan accused US President Donald Trump on Monday of seeking to divide communities in Britain after the leader of the free world criticised his leadership following a terror attack in the city.
"My focus from Saturday night has been working with the police the emergency services and the government to deal with the horrific attack on Saturday", Khan told Sky News, when asked about Trump's latest tweet.
The White House on Monday denied suggestions from USA reporters that Trump "picked a fight" with Khan "because he was Muslim".
An Irish security source described the murderer as having "extensive immigration history related to the UK".
At around 1.30am on Tuesday counter-terror officers raided a property in Ilford, east London.
They had been held following police raids at two addresses in Barking, east London, the area where the known attackers lived.
Forty-eight others were wounded in the attacks, and the English health authority said Sunday that 21 people remain in critical condition.
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It was the third attack in as many months where suspects had been on the radar of British authorities.
Six women and four men arrested by police after the attack are still being questioned, police said. Two others arrested had been released previously.
The Islamic State terror group, also known as Daesh, has claimed the London Bridge rampage, while the attack has sparked fears Britain is in the grip of a spate of copycat incidents. "They are particularly keen to hear about places they may have frequented and their movements in the days and hours before the attack".
In the documentary, Butt can be seen praying in a London park.
One of the attackers was shown in a photograph lying on the ground outside the Wheatsheaf pub.
"When you have a special relationship it is no different from when you have got a close mate".
"London stands in defiance against this cowardly attack on our city, our people, our values and our way of life".
He told GMB: "I can't follow 400 people".
During that time, police numbers have dropped by roughly 20,000 officers, and the number of armed officers has fallen as well. One of them was an Arsenal fan.
The majority of us can distinguish between hate organizations founded by Christians and Christianity and yet cannot get our heads around the fact that extremism perpetuated by some misguided individuals in the name of Allah has nothing to do with the peaceful religion that is Islam.