London attack is latest in which vehicles are used as weapon

A body is covered by a sheet outside the Houses of Parliament, London, Wednesday, March 22, 2017. London police say they are treating a gun and knife incident at Britain's Parliament "as a terrorist incident until we know otherwise." The Metropolitan Police says in a statement that the incident is ongoing. It is urging people to stay away from the area. Officials say a man with a knife attacked a police officer at Parliament and was shot by officers. Nearby, witnesses say a vehicle struck several people on the Westminster Bridge. (Stefan Rousseau/PA via AP). (The Associated Press)

Tourists view parliament from across the River Thames, with Westminster Bridge, right, in London, Thursday March 23, 2017, the scene of an attack. On Wednesday a knife-wielding man went on a deadly rampage, first driving a car into pedestrians then stabbing a police officer to death before being fatally shot by police within Parliament's grounds in London. (AP Photo/Tim Ireland) (The Associated Press)

LONDON – When an attacker plowed a vehicle into pedestrians on London's Westminster Bridge on Wednesday, it was the latest in a string of incidents in which drivers used their vehicles as weapons.

Some were orchestrated by extremist groups, others by unstable individuals with unclear motives. While no one so far has claimed responsibility for Wednesday's attack in London, radical groups have urged supporters to use any weapons at hand — including cars. The tactic presents a major challenge for security forces around the world.

___

MARCH 22, 2017

A vehicle mowed down pedestrians on London's Westminster Bridge, killing two people and leaving others with injuries described as catastrophic. Around the same time, a knife-wielding attacker stabbed a police officer and was shot on the grounds outside Britain's Parliament. Authorities were treating the attacks as a terrorist incident.

___

JAN. 20 , 2017

A man with a history of mental health and drug abuse issues drove into a street crowded with pedestrians in Melbourne, Australia's second-largest city, killing at least four people, including a child, and injuring around 15 others. The 26-year-old man was arrested, and police said the incident had no links to terrorism.

___

DEC. 2016

A young Tunisian rammed a truck into a crowded Berlin Christmas market, killing 12 and injuring dozens in an attack claimed by the Islamic State group. It was the first mass casualty attack by Islamic extremists carried out on German soil. Attacker Anis Amri, who had been denied asylum in Germany, was killed by police in Italy after an international manhunt.

___

JULY 14, 2016

A Tunisian residing in France plowed a refrigerator truck through a crowd celebrating Bastille Day on the Mediterranean beachfront in Nice, killing 86. Attacker Mohamed Lahouaiej Bouhlel, who claimed allegiance to the Islamic State group, was killed by police. Cities around the world beefed up measures to prevent vehicle attacks in response.

___

DECEMBER 2014

A motorist injured 13 pedestrians in the French city of Dijon; a day later, a man ran over pedestrians at a Christmas market in Nantes in western France, killing one and injuring nine. Both suspects, who survived, had histories of mental illness.

___

OCT. 20, 2014

A 25-year-old man drove his car into to Canadian Air Force members near Montreal, killing one of them and injuring another. Authorities said the driver was a convert to Islam and had been flagged for jihadist ambitions. He was later shot dead by police.

___

JUNE 30, 2007

Two men attempted to crash a blazing Jeep loaded with explosives into Glasgow Airport in Scotland. The car's path was blocked and the explosives failed to detonate.

Antisemitism Exposed