"It has now been confirmed sadly that seven members of the public have died. In addition, as you know, we believe, three suspects are dead," London's Metropolitan Police chief Cressida Dick said in a televised statement.
The patrols will be increased in many areas of the city, the chief said, adding that the patrols will include armed officers.
According to the London Met Police, their priority is "to work with counter-terrorism police colleagues to establish more details about the attackers."
"This is a very worrying time for people," Cressida Dick said. "I would ask Londoners and visitors to remain calm and be vigilant."
Asked about the threat level having been lowered to "severe" rather than "critical," Dick said that the police were prepared for a potential incident and dealt with it within 8 minutes.
"Our understanding is there were three attackers <…> We have witness reports about three people armed with knives <…> The threat that they posed was neutralized within eight minutes," Dick pointed out. "We don't believe any suspects are at large but need to make absolutely sure."
Asked whether she knows the identity of suspects in London Bridge attack, Dick said that she didn't.
London Metropolitan Police Chief assumed that her team "will be sharing information" with their American colleagues.
"Our priority now is to work with our colleagues in the national counter-terrorism police network and also with the intelligence agencies and other security services to establish more details about these individuals who carried out the attack and the background to it," she said.
UK Prime Minister Theresa May said Britain's Conservative Party is suspending national campaigning ahead of the general election on June 8 as a result of the terror attacks in London.
Britain's opposition Labour Party showed solidarity with its primary opponent, suspending its national election campaign until Sunday evening following an attack in London which killed six people, party leader Jeremy Corbyn said in a statement.
UK Independence Party (UKIP) refused to suspend their election campaign, saying that "disrupting our democracy is what the extremists want."
