UPDATE: 5:10 p.m. EDT — The Islamic State group (ISIS) Sunday claimed responsibility for Saturday’s London Bridge attack that left seven dead and 48 injured.

"A detachment of Islamic State fighters executed yesterday's London attack," a statement posted on Amaq's media page said.

UPDATE: 3:40 p.m. EDT — Facebook issued a statement Sunday, saying it intends to become a “hostile environment” for terrorists.

"We want Facebook to be a hostile environment for terrorists," said Simon Milner, director of Policy at Facebook.

"Using a combination of technology and human review, we work aggressively to remove terrorist content from our platform as soon as we become aware of it — and if we become aware of an emergency involving imminent harm to someone's safety, we notify law enforcement."

The statement was emailed to Reuters.

UPDATE: 3:35 p.m. EDT — London Mayor Sadiq Khan rejected U.S. President Donald Trump’s tweet about the London attack but declined to respond directly.

“He has more important things to do than respond to Donald Trump’s ill-informed tweet that deliberately takes out of context his remarks urging Londoners not to be alarmed when they saw more police — including armed officers — on the streets,” a spokesman for the mayor said in a statement.

Trump ridiculed Khan for saying Londoners “should not be alarmed” in the wake of Saturday night’s attack.

In an interview with the BBC, Khan said Londoners should not be alarmed by an increased police presence in the next few days because they were making sure London was “one of the safest global cities in the world.”

Original story

Promising “enough is enough,” Prime Minister Theresa May called for a thorough review of Britain’s counterterrorism approach Sunday following Saturday night's knife rampage, the country’s third major terrorist attack in three months.

Seven people were killed and 48 injured, 21 critically, in an assault near the London Bridge and Borough Market areas. Metropolitan Police said 12 arrests had been made in the east London section of Barking.

The attackers drove a van onto a sidewalk on London Bridge around 10 p.m., hitting a number of pedestrians, police said, then jumped out and started stabbing people in nearby bars and restaurants. Within eight minutes, police killed the three attackers, firing 50 rounds, a fusillade Assistant Counterterrorism Commissioner Mark Rowley called unprecedented.

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"Since the emergence of the threat from Islamist-inspired terrorism, our country has made significant progress in disrupting plots and protecting the public. But it is time to say enough is enough," May said.

The attack comes just days before Britain’s national elections and just after the government lowered the threat level from “critical” to “severe” in the wake of the May 22 Ariana Grande concert carnage in Manchester that left 23 dead and 119 injured. On March 22, a man drove a car into pedestrians on the pavement along the south side of Westminster Bridge, injuring 50 people.

READ: London Bridge Terror Attack: Why Vehicles Are Becoming Common Weapons

Early Sunday, May’s Conservative Party and rival Labour Party suspended campaigning as a sign of respect for the victims. The U.K. Independence Party declined to take part in the tribute.

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After May said the election would continue Thursday as planned, she held an emergency meeting with her security cabinet. After the session, she said the government would bolster its counterterrorism efforts and try to decrease or remove “the safe spaces it [terrorism] needs to breed.”

“Everybody needs to go about their lives as they usually would,” she said. “Our society should continue to function in accordance with our values. But when it comes to taking on extremism and terrorism, things need to change,” she said.

The London Bridge was closed off after the attack. British Transport Police tweeted the bridge would be shut down for the remainder of the night. Law enforcement asked people to stay away from both the London Bridge and Borough Market areas.

London Police said a stabbing near Vauxhall, not far from London Bridge and Borough Market, was unrelated to the terrorist attack.

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A White House spokesperson said U.S. President Donald Trump had been briefed by his national security advisers on the London events and then headed to Trump National Golf Club in Virginia.

READ: Trump On Climate: Pruitt Says Paris Agreement Ineffective; Gore Says Pullout Reckless [VIDEO]

President Trump took to Twitter to comment on the terrorist attack, suggesting that America needs the travel ban as a precautionary measure.

Susan Rice, the former U.S. ambassador to the United Nations and a former national security adviser, told ABC's "This Week" Trump’s tweets were ill-advised.

“Unfortunately, this is — something that the people of the United Kingdom have suffered now three times in the last three months. And it's important to begin by expressing our condolences and to say that our thoughts and prayers go out, yet again, to the people of London and the United Kingdom,” she said.

“Clearly the terrorist threat is one we have been dealing with for many, many years both in Europe, and the Middle East, and of course in the United States. And what is important in these times is to remain unified, to be vigilant, and to recognize that this is a long-term challenge to stamp out the threat of terrorism.

“We are battling ISIS in Syria and Iraq, al Qaeda and ISIS in Afghanistan. And we see elements of the terrorist threat in all parts of the world from Africa to the Middle East to Southeast Asia.”

On CBS' "Face the Nation" Sen. Mark Warner, D-Va., vice chairman of the Senate Intelligence Committee, warned Trump against using the London attack as a basis for a travel ban against Muslims, saying such a ban could "incite more incidents." He also called on companies like Facebook, Twitter and Google to recognize "there may need to be some responsibility to curate information" in light of the incidence of self-radicalization.