LONDON, U.K. (AP) - Prime Minister Theresa May called Sunday for tougher measures to contain Islamic extremism in Britain in the wake of an attack that killed seven people in a busy area of London.
The assault began Saturday night when a van veered off the road and barreled into pedestrians on busy London Bridge. Three men fled the van with large knives and attacked people at bars and restaurants in nearby Borough Market, police and witnesses said. The attack unfolded quickly, and police said officers had shot and killed the three attackers within eight minutes.
Emergency officials said 48 people were treated at London hospitals and a number of others suffered less serious injuries.
Britain was already on edge after a suicide bombing two weeks ago at an Ariana Grande concert in Manchester, in northwest England, that killed 22 people and injured dozens of others. Grande and other stars are scheduled to perform a benefit concert for victims Sunday night.
The Islamic State group claimed responsibility for the Manchester bombing, but there has not yet been a claim of responsibility for the London attack.
May, who faces a general election Thursday, said the recent attacks are not directly connected but that "terrorism breeds terrorism" and attackers copy one another. She also said five credible plots have recently been disrupted.
"They are bound together by the single evil ideology of Islamist extremism that preaches hatred, sows division, and promotes sectarianism," she said. "It is an ideology that claims our Western values and freedom, democracy and human rights are incompatible with the religion of Islam."
She called for international agreements to regulate cyberspace to help stop the spread of extremism and said Britain needs to become more robust at identifying and stamping it out.
"That will require some difficult, and often embarrassing, conversations," she said.
The violence turned a summery night in an area packed with revelers into a scene of panic and chaos, with officers running through crowded streets screaming for people to flee. Lifeboats on the River Thames helped evacuate the area, which is popular with tourists. It remained closed off Sunday and police urged residents and tourists to stay away.
May said the men attacked "innocent and unarmed civilians" in Borough Market with blades and knives. She said they were wearing what appeared to be explosive vests, but police determined those were only meant to sow panic and fear.
May's Conservative Party had been expected to win by a wide margin but recent polls have showed the race tightening. Major parties temporarily suspended national campaigning Sunday.
London Mayor Sadiq Khan said the attackers hoped to disrupt democracy and hamper plans for voting, but that would not happen. He said Londoners should remain vigilant but added: "I'm reassured we are one of the safest global cities in the world."
Assistant Metropolitan Police Commissioner Mark Rowley said that while police believe all the attackers were killed, the investigation continued.
"We believe three people were involved, but we still have got some more inquiries to do to be 100 percent confident in that," he said.
As dawn broke over the capital, a large area on the south bank of the River Thames remained cordoned off. Police told people to avoid the area, leaving tourists and revelers struggling to get home.
Khan said some of the injured were in critical condition. French and Spanish citizens were among the wounded.
Only hours before, bursts of gunfire echoed through the streets -- likely from armed police -- and at least three blasts rang out as officers performed controlled explosions.
Gerard Vowls told The Guardian newspaper that he saw a woman being stabbed by three men at the south end of London Bridge. He said he threw chairs, glasses and bottles at the attackers in a bid to stop them.
"They kept coming to try to stab me. They were stabbing everyone. Evil, evil people," he told the newspaper. "I want to know if this girl is still alive. I've been walking around for an hour and a half crying my eyes out. I don't know what to do."
Bartender Alex Martinez said he hid in a garbage bin for a half hour when a man stormed the restaurant where he worked, which was nearly full.
"I saw that man with a knife in his hand and after that a man started screaming so I knew something wrong was happening," he said.
Medics treated the injured near the market as shocked people cried and shouted around them. Police officers yelled at people to run from the area.
Simon Thompson told Sky News that he was just outside Borough Market when he saw crowds fleeing.
"We ran for like 100 meters and then saw loads of police cars turned up and there was kind of a period of quite intense gunfire," he said. "I hid in a restaurant basement for about an hour. ... Police told us to get out and then there was more gunfire."
Police received the first call of reports of a vehicle hitting pedestrians on London Bridge at 10:08 p.m. (2108 GMT).
Soon after, reports started coming in of stabbings at Borough Market, a nearby area full of bars and restaurants surrounding a popular food market.
Photographer Gabriele Sciotto said he was on his way home from a pub when he saw a man running toward him telling him to turn around and run because there was a terrorist attack. As a documentary filmmaker, though, his instincts were to keep going.
The 25-year-old said that at first, "it didn't look too dangerous."
The men went into Borough Market, but then turned around and ran toward the Wheatsheaf Pub after being confronted by a police officer, he said, and suddenly a lot of police came from the other direction.
The attackers "had no clue what they were doing. They were scared. The police were scared," he said.
After one of the men was shot, Sciotto captured a photo of the suspect on the ground wearing what appeared to be canisters.
Police initially said officers were also responding to a third incident, in the Vauxhall neighborhood, but later said that turned out to be an unrelated stabbing.
Police tweeted a warning telling people in the area to run to safety, hide and then call police if it is safe to do so. They asked Londoners to "remain calm but be alert and vigilant."
It was the third attack to hit Britain in as many months.
In March, a British convert to Islam ran down people with a vehicle on Westminster Bridge, killing four, then stabbed a policeman to death outside Parliament.
Then came the May 22 Manchester concert bombing. After that attack, Britain's official terrorism threat level was raised to "critical," meaning an attack may be imminent. Several days later it was lowered to "severe," meaning an attack is highly likely.
Department of Homeland Security's Statement on London Attack:
"The Department of Homeland Security is closely monitoring the ongoing situation in the United Kingdom. We are working with our interagency partners and foreign counterparts to gain further insight into reported attacks against civilians on London Bridge and in the surrounding area. U.S. citizens in the area should heed direction from local authorities and maintain security awareness.
"We encourage any affected U.S. citizens who need assistance to contact the U.S. Embassy in London and follow Department of State guidance. The Secretary has been fully briefed on the incidents and the ongoing response. At this time, we have no information to indicate a specific, credible terror threat in the United States. We are in contact with and stand ready to assist our friends and allies in the United Kingdom as they respond, investigate, and recover. Our thoughts and prayers are with those affected by these incidents."
Statement from London's, Mayor Sadiq Kahn:
"The Metropolitan Police are responding to the horrific terrorist attack at London Bridge and Borough Market. My thoughts are with everyone affected, and I'd like to thank the brave men and women of our emergency services who were first on the scene and will be working throughout the night. I am in close contact with the Met Commissioner and senior officers and am being kept updated on all developments. I will be attending the government's emergency Cobra meeting later this morning.
"London Bridge Station is closed and we are asking people to avoid the area. The situation is still unfolding and I would ask all Londoners and visitors to our city to remain calm and vigilant. Please report anything suspicious to the police, but only call 999 in an emergency. We don't yet know the full details, but this was a deliberate and cowardly attack on innocent Londoners and visitors to our city enjoying their Saturday night. I condemn it in the strongest possible terms. There is no justification whatsoever for such barbaric acts. For further updates or information please follow the Metropolitan Police on Twitter: www.twitter.com/metpoliceuk"