Terror struck at the heart of London when three knife-wielding attackers wearing fake suicide vests unleashed a rampage through central London, first plowing a van into pedestrians on the iconic London Bridge and then running to nearby Borough Market where they randomly stabbed multiple people, killing seven and injuring at least 40 others.
The attack at the two key London landmarks last night came just days before the general election on June 8 and was the third such strike to hit Britain in as many months.
The three attackers were shot dead after eight minutes of terror, police said.
The first incident was reported at the London Bridge when a van swerved off the road into a crowd of pedestrians. A white van driver came speeding veered off the road into the crowds of people who were walking along the pavement, an eye-witness was quoted as saying by BBC.
Within minutes, there were reports of a second attack at Borough Market on the south bank of the Thames where three men wielding knives 10 inches long began attacking passersby, even entering one restaurant to attack night diners.
The Metropolitan police on Sunday morning said six civilians were killed but later updated the toll to seven.
"We took 48 patients to five hospitals across London and treated a number of others at the scene for minor injuries," London Ambulance Service said in a statement.
"We declared a major incident and continue to work closely with other members of the emergency services at the scene," it said.
The British Transport Police said one of its officers was seriously injured after being stabbed as he responded to the incident, but his condition was not said to be life- threatening.
There was no immediate claim of responsibility.
The three assailants shot dead by police were wearing fake suicide vests, police said today.
"The suspects were wearing what looked like explosive vests but these were later established to be hoaxes," Britain's head of counter-terrorism Mark Rowley said.
A large area of central London remained cordoned off and police told people to avoid the area, leaving tourists and revellers struggling to get home.
Bursts of gunfire echoed through the streets - likely from armed police - and at least three blasts rang out as police performed controlled explosions.
Police also said that they were attending a third incident in the Vauxhall area, but later said it was not connected.
It was the third terror attack to strike the UK this year, after a man drove a car into pedestrians on Westminster Bridge in March and the bomb attack on an Ariana Grande concert in Manchester two weeks ago.
The Indian High Commission in London has set up a Public Response Unit for any Indians caught up in the attack.
"Any Indians injured/affected during the London Bridge 'major incident' and at Borough Market may reach off-office hours Public Response Unit. We shall endeavour to extend all possible assistance to all affected and to their families and friends in this difficult hour," an Indian High Commission statement said.
Prime Minister Theresa May said that the "terrible incident" in London is being treated as a "potential act of terrorism".
The prime minister said: "Following updates from police and security officials, I can confirm that the terrible incident in London is being treated as a potential act of terrorism".
London Mayor Sadiq Khan called it "a deliberate and cowardly attack on innocent Londoners".
Jeremy Corbyn, the Opposition Labour leader, tweeted on Sunday night: "Brutal and shocking incidents reported in London. My thoughts are with the victims and their families. Thank you to the emergency services".
Tim Farron, the Liberal Democrat leader, said: "Tonight's horrific incidents in London remind us how much we owe our emergency services. My thoughts and prayers with everyone affected".
Nicola Sturgeon, the Scottish First Minister and SNP leader, wrote on Twitter: "Dreadful news from London. My thoughts are with all those affected.
The election campaigning has been suspended in the wake of the attack.
A spokesman for the Theresa May's Conservative Party confirmed the party had suspended election campaigning.
"The Conservative Party will not be campaigning nationally today. We will review as the day goes on and as more details of the attack emerge," the spokesman said.
Jeremey Corbyn's Labour Party is also expected to make the announcement soon.
The incidents, just four days before the general election on June 8, come less that two weeks after a suicide bomber targeted a Manchester concert on May 22, killing 22 victims.
On May 22, 22 people were killed and 116 injured in a suicide bombing at Manchester Arena.
On March 22, six people died, including the attacker, and at least 50 people were injured in an attack near the Houses of Parliament.