Investigators believe three victims were killed on the bridge, including one man who was thrown into the River Thames, before the attackers left the vehicle and stabbed five people to death around London's busy Borough Market, Haydon said.
They have also obtained a warrant to prolong the detention of a 27-year-old man arrested under the Terrorism Act on Tuesday. Eight people were killed and dozens wounded.
Police killed all three attackers.
"The threat is changing", she said.
She said that includes "whether you see something suspicious, you know somebody who has started to behave strangely, you are hiring a vehicle to somebody and you have concerns about them". "And this happened in England, absolutely".
The final attacker was named as Youssef Zaghba, a 22-year-old Italian national of Moroccan descent and lived in east London.
Butt, who was born in Pakistan and moved to Britain as a child, had worked in 2015 in the office at Auriga Holdings Ltd, which manages some Kentucky Fried Chicken franchises in Britain.
Germany's Merkel lends support to Mexico over NAFTA
Brexit talks will begin as planned in the "next couple of weeks", German Chancellor Angela Merkel and Theresa May have agreed. There are around 1,900 German companies operating in Mexico such as Siemens, BMW and Volkswagen, generating 120,000 jobs.
"According to him IS, whatever they are doing killing innocent people, he says it is quite justified".
It is claimed that he knew Siddhartha Dhar, a Hindu who converted to Islam and joined Isis in Syria.
Then, eight weeks later, three extremists staged a carbon-copy attack on London Bridge.
Youssef Zaghba, 22, the son of an Italian mother and Moroccan father, was reportedly stopped at Italy's Bologna Guglielmo Marconi Airport previous year as he was headed to Syria via Turkey.
Italian authorities said Zaghba had been stopped and questioned in Italy but had not been charged with any crime.
Anyone with information can call the police in confidence on 0800 789 321 or visit gov.uk/ACT and complete a secure form.
"The majority of them have a domestic focus, if I can put it that way, a domestic centre of gravity", she said.
His passport and cellphone were seized, but he got them back after a court determined there wasn't enough evidence to arrest him.
Stonewall: Conservatives must not derail LGBT equality for deal with DUP
And that is only if she survives long enough to actually make it to the negotiating table - a big if. Combined, the Tories and the DUP - which won 10 seats - would have 329 MPs in the Commons.
Material tethered to one hilt is shown saturated with blood and was apparently designed so killer Khuram Butt could strap it to his wrist, Met Police commander Dean Haydon said. "We won't let them win and London will carry on", she said.
"London is an incredibly resilient city", she said.
"We are so proud of Kirsty's fearless actions which demonstrate how selfless, caring and heroic she was, not only on that night, but throughout all of her life", they added. "And after I thought that these images of a garden were similar to the images of paradise".
All three of the attackers were armed with pink ceramic knives, believed to have been bought from a Lidl store.
Butt's family said Wednesday they were "shocked and appalled" by his actions.
Haydon said his teams were working flat out: "We also need to watch out for those who may be inspired by these recent attacks".
Up to two-thirds of all terror plots involving United Kingdom nationals at home and overseas in the previous two decades had been linked to the group according to the sources, including the 2005 London bombings, the murder of British soldier Lee Rigby in east London in 2013 and a copycat plot in August 2014 to behead another British soldier in the capital.
Comey testimony is done - now the spin begins
When asked to comment on Trump's excuse for firing him, Comey said: " Those were lies, plain and simple ". He also said that Trump told him during a private White House dinner: "I need loyalty".
- Men planned to use 7.5 tonne lorry — LONDON TERROR ATTACK
- Keller @ Large: Absurd Moment From James Comey's Testimony
- Trump Addresses Infrastructure, Health Care in Ohio
- India urges Gulf nations to resolve Qatar crisis through talks
- Nadal, Djokovic can set up French Open semifinal showdown
- Jeremy Corbyn: Labour is ready to serve the country
- Professor eats his pro-Brexit book after election stunner
- The CytRx (CYTR) Earns Coverage Optimism Rating of 0.17
- Sturgeon: "Scotland will be independent"
- European Union ready for Brexit negotiations, says Merkel