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Is The London Bridge Incident Related To The Westminster Attack In March? It Depends Who's Responsible

As reports unfolded late Saturday night of a vehicle plowing into pedestrians on London Bridge, followed by two other incidents in the British capital, one question on many people's minds was, Is the London Bridge incident related to the Westminster attack in March? The violence began Saturday when a van ran down pedestrians on the bridge, according to CNN, and continued south of the bridge when a man reportedly stabbed two individuals in a restaurant at Borough Market. There were also reports of shots heard following the bridge incident.

UPDATE: The London Bridge attack has since been declared a terrorist incident, according to the Associated Press. London Metropolitan Police Commissioner Cressida Dick on Sunday confirmed that the death toll in the London Bridge attack had been raised to seven, not including three of the attackers, with at least 48 others injured. Dick added that the remaining injured had been transported "to five hospitals across London." Some were in critical condition. The three attackers "were fatally shot by officers within eight minutes of the first emergency call," according to The Washington Post. An additional 12 people have also been arrested in connection with the attack.

The nearby Vauxhall stabbing was later declared not to be part of the London Bridge attack, but a separate incident.

EARLIER: As many people noted with dismay on Twitter, it all felt very familiar. On March 22, a lone attacker mounted the sidewalk on Westminster bridge near British parliament, hitting multiple pedestrians, the BBC reported. Five people died before law enforcement fatally shot the assailant. ISIS claimed responsibility for the Westminster attack, according to The Independent.

In order to know whether the two attacks are related, authorities will need to first know who is responsible for the incidents Saturday night. And even then it may not be clear. For example, if ISIS claims responsibility, that will not necessarily mean that the two attacks were planned together or by the same group of people. As The Independent noted, "Isis frequently claims responsibility for terror attacks that it has not directly orchestrated or facilitated."

The London Bridge and Westminster attacks do have one major thing in common: the use of a vehicle as a weapon, which is a hallmark of recent ISIS attacks. ISIS claimed responsibility for the July 14, 2016 attack in Nice, France in which a cargo truck plowed into pedestrians on the Promenade des Anglais, killing dozens of civilians, the BBC reported.

Lots of people also mentioned the May 22 attack at an Ariana Grande concert in Manchester, which killed 22 people, many young women and girls, in tweets suggesting that the United Kingdom is currently being subjected to a sustained terror campaign. ISIS claimed responsibility for that attack as well.

So far, authorities have only said that the London Bridge and Borough Market incidents are being treated as terrorist attacks, and that they are believed to be linked.

Following the Westminster attack, British Prime Minister Theresa May said, "The police have no reason to believe there are imminent further attacks on the public."