Two of the previous three attacks took place in London, where pedestrians were struck by vehicles. The first was in Westminster in March and the second was a fortnight ago in London Bridge.
In addition, a suicide bomber targeted a pop concert in Manchester in May, killing 23 people.
The country is unsettled, but consistently, the loudest message that emerges is one of unity.
Al Jazeera’s Jonah Hull reports from London.
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Categorised in: International