Elite women runners leave the start line of the 118th Boston Marathon on 21 April 2014
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Boston marathon honours bomb victims

21 April 2014 Last updated at 23:58 BST

Thousands of marathon runners have taken to the streets of Boston, after the city honoured three killed and more than 260 injured in a bomb attack last year.

A moment of silence was held before some 36,000 people got off the starting blocks.

Officials mounted a huge security operation ahead of the race, which included a ban on rucksacks and screening at checkpoints.

Nick Bryant reports.