Seven people, including one Canadian, have been killed by attackers who drove a van at high speed into pedestrians on London Bridge and then stabbed revellers in the nearby Borough Market area on Saturday night.

It was Britain’s third militant attack in as many months and took place five days before the upcoming national election on Thursday, which British Prime Minister Theresa May said would go ahead as planned.

May said the perpetrators were Islamist militants and called for a tougher counterterrorism strategy. All three attackers were shot dead by police within minutes of the first emergency call being made.

Here’s what is known about the attack so far:

How did the attack unfold?

The attack started at 9:58 p.m. local time, Mark Rowley, Britain’s top counterterrorism police officer, said.

Three attackers drove a white van at high speed, from north to south, into pedestrians walking on London Bridge, police said. Rowley said the van had been recently hired by attackers.

A witness said at least six people were hit on the bridge.

“It looked like he was aiming for groups of people. I froze because I didn’t know what to do,” Mark Roberts, a 53-year-old management consultant, told Reuters. “It was horrendous.”

Police said they responded to the incident on London Bridge at 10:08 p.m.

Britain London Bridge

In this image made from PA Video footage, people receive medical attention in Thrale Street, near the London Bridge. (Federica De Caria/PA/Associated Press)

After the incident on the bridge, the three men abandoned the vehicle, ran down a set of stairs and began attacking people with knives in the nearby Borough Market area on the south side of the Thames, police said.

The neighbourhood is best known for its 1,000-year-old food market but is also home to many popular pubs and restaurants. Witnesses said the attackers stabbed people in the street, as well as those in pubs and restaurants.

“Armed response officers then responded very quickly and bravely and confronted the three male suspects who were shot and killed on Borough Market,” Rowley said. “The suspects were wearing what looked like explosive vests but these were later established to be hoaxes.”

Rowley said that eight officers fired about 50 bullets at the men — an “unprecedented” amount for British police. A member of the public received a non-critical gunshot wound as a result, he added.

One of the attackers was shown in a photograph lying on the ground outside the Wheatsheaf pub. Another man, also reported to be an attacker, was pictured on the ground a short distance away.

“We believe that the threat that they posed was neutralized in eight minutes,” Metropolitan Police Commissioner Cressida Dick told reporters.

Who was involved in the attacks?

At 12:25 a.m. local time Sunday, the attacks at London Bridge and Borough Market were declared terrorist incidents.

Rowley said he was “increasingly confident” that the three individuals who conducted the attack had been killed, but that police were working to establish whether any associates were involved in the planning.

May said the attacks were inspired by what she called a “single, evil ideology of Islamist extremism” that represented a perversion of Islam and of the truth.

Britain’s “COBRA” emergency response committee, which includes intelligence and security chiefs as well as senior ministers, met on Sunday.

‘Enough is Enough’, British PM Theresa May condemns London attacks2:22

Afterward, May said there was no direct relationship between the London Bridge attack, the suicide bombing at a concert in Manchester that killed 22 people two weeks ago, and another vehicle and knife attack in Westminster in March which killed five people.

She called for a review of counterterrorism strategy.

“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.

The SITE Intelligence Group said on Sunday ISIS claimed responsibility for the attack.

SITE said in a statement that the Islamic State in Iraq and Syria’s Aamaq news service cited “a security source” in the Arabic-language posting claiming the attack.

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People lie on the ground after being detained by police at Elizabeth Fry apartments in Barking, east London, which officers raided on Sunday. (Furqan Nabi/Press Association via AP)

Police arrested 12 people on Sunday in the Barking area of east London in connection with the attack.

A Reuters photographer saw four women being escorted into the back of police vans. British police also searched an address in nearby East Ham.

Who are the victims?

Seven people were killed in the attack, including one Canadian and one French citizen.

Christine Archibald, from Castlegar, B.C., was struck on London Bridge, where she was walking with her fiancé, according to the fiancé’s siblings. A statement from her family recalled the 30-year-old as someone with a big heart, who had been working in a homeless shelter before she moved to Europe.

“We grieve the loss of our beautiful, loving daughter and sister. She had room in her heart for everyone and believed strongly that every person was to be valued and respected,” the statement read. “She would have had no understanding of the callous cruelty that caused her death. Please honour her by making your community a better place.”

Christine Archibald and Tyler Ferguson

Christine Archibald with her fiancé, Tyler Ferguson. Archibald was one of the victims of the attack in London. (Mark Ferguson/Facebook)

A French national was also among the victims, the country’s foreign ministry confirmed Sunday.

Forty-eight others were wounded in the attacks, and the English health authority said Sunday that 21 people remain in critical condition.

Australia’s Foreign Minister Julie Bish said three Australians have been injured in the knife attacks.​

What are the political implications?

The United Kingdom is due to hold a national election on Thursday, and officials said the vote would not be postponed.

Major political parties suspended national campaigning for the June 8 election in the wake of the attack, with the exception of the anti-European United Kingdom Independence Party.

The Theresa May-led Conservatives were far ahead in polls, but their lead has narrowed in recent days.


Ameer Hussein, 2, lays flowers near the scene of last night’s terror attack. (Christopher Furlong/Getty Images)

Saturday’s attack came less than two weeks after a suicide bomber Salman Abedi blew himself up at a concert in Manchester on May 22.

Britain raised its terror threat to the highest level of “critical” and deployed troops on the streets on May 23, a day after the Manchester suicide attack. The critical level means another attack could be imminent. It was reduced to “severe”, which means an attack is highly likely, on May 27.

And on March 22, Khalid Masood plowed a rented car into pedestrians on Westminster Bridge in London and stabbed a policeman to death before being shot dead. His attack killed five people.

May said Sunday that police had recently foiled five other plots.