British police have arrested 12 people after seven people were killed and dozens injured in a terror attack in London.
The arrests in Barking, east London, on June 4 followed a raid at a flat belonging to one of the three attackers.
A van hit pedestrians on London Bridge at around 10 p.m. local time on June 3, then three men got out of the vehicle and stabbed people in nearby Borough Market before being shot dead by police.
The three attackers were wearing suspected explosive vests that were later found to be fake.
London police said the assailants were shot dead by eight officers who fired 50 bullets.
Assistant Commissioner Mark Rowley, the force's head of counterterrorism, said a member of the public was accidentally shot and remained in hospital in a non-critical condition.
He said 36 people were in hospital with a "range of injuries" and 21 were in a critical condition.
A French and Canadian citizen were among those killed.
No group has so far claimed responsibility for the terror attack -- the third in Britain since late March following a similar attack on March 22 near Parliament on Westminster Bridge and a bombing at a pop concert U.S. pop singer Ariana Grande in Manchester on May 22.
A charity concert on June 4 was being held for victims of the Manchester attack, featuring Grande, Justin Bieber, and other stars.
The "One Love Manchester" concert at the Old Trafford cricket grounds in Manchester was attended by some 50,000 people.
British Prime Minister Theresa May said "enough is enough" when it comes to tackling terrorism.
May announced on June 4 that the country’s counterterrorism strategy would be reviewed, saying, "We cannot and must not pretend that things can continue as they are."
Authorities said the London Bridge incident started when the attackers drove a white van off the roadway and mowed down several pedestrians.
They then went to nearby Borough Market, where they stabbed several people in the popular area filled with restaurants and bars before being shot down by police within eight minutes after the first emergency call were received.
WATCH: Londoners Flee After 'Terrorist' Attacks
BBC reporter Holly Jones, who was on London Bridge, said she saw a van "probably traveling at about 50 miles [80 kilometers] an hour."
"He swerved right round me and then hit about five or six people," Jones reported.
At Borough Market, witnesses said three men armed with knives stormed into bars and restaurants, stabbing people at random as patrons and staff fled or hid inside the establishments.
"They were stabbing people... We were shouting 'stop, stop' and people threw chairs at them," a chef at one restaurant told the dpa news agency. "Police came and shot [the attackers] straight away."
Most political parties suspended national general election campaigning following the attack, but Prime Minister May said full campaigning would resume on June 5 and the general election would go ahead as planned on June 8.
"Violence can never be allowed to disrupt the democratic process," she said.
May added that, while the recent attacks in Britain are "not connected" by common networks, they indicate a "new trend in the threat we face as terrorism breeds terrorism."
The attacks were bound together by an "evil ideology" that is a "perversion of Islam and perversion of the truth," the prime minister said.
She also said British authorities had disrupted five credible plots since March.
London Mayor Sadiq Khan called the attackers "evil cowards," and said London "will never be cowed."
"We will never let them win," he added.
He also said Londoners would see an increased police presence in the city and urged them to remain "calm and vigilant."
Police said that they were "reviewing and planning to strengthen our policing stance across London over the forthcoming days."
Britain has been under high alert after recent terror incidents and ahead of the June 8 general election.
On March 22, three people were killed and at least 29 were hurt when a driver struck pedestrians on Westminster Bridge near Parliament. The car then crashed into the fence around Parliament and the driver attacked an officer with a knife.
More recently, a suicide bomber killed 22 people at a music concert by U.S. pop singer Ariana Grande in Manchester on May 22.
A charity concert for victims of the Manchester attack, featuring Grande, Justin Bieber, and other stars, is due to be held in the northwestern English city later on June 4.
Trump Offers 'Full Support'
World leaders offered support following the latest attack in London.
"In the face of this new tragedy, France is more than ever at Britain's side," French President Emmanuel Macron wrote in a tweet. "My thoughts go out to the victims and their loved ones.”
German Chancellor Angela Merkel said her country stood "firm and resolute" by Britain's side in the fight against terrorism. "We are united in horror and grief, but also in determination," she said in a statement.
Russian president Vladimir Putin expressed his condolences in a telegram to the British prime minister, the Kremlin said.
"The President of Russia expressed his confidence that the buildup of joint efforts to fight forces of terror all over the world should become the common answer on what happened," a statement said.
In a statement, U.S. President Donald Trump praised the "heroic response of police and other first responders and offered the full support of the United States government in investigating and bringing those responsible for these heinous acts to justice."
Earlier, Trump called in a tweet for a temporary travel ban on visitors from six predominantly Muslim countries to be implemented.
"We need to be smart, vigilant and tough. We need the courts to give us back our rights. We need the Travel Ban as an extra level of safety!" he wrote.
The Trump administration has asked the U.S. Supreme Court to review the legality of the president's executive order on the travel ban, which has been blocked by a series of court rulings.
With reporting by Sky News, the BBC, Reuters, AFP, AP, dpa, and Interfax