Brighton runner Abi Griffiths crossed the finish line of the Boston Marathon around ten minutes before the explosions happened.
She said: "It was as I was retrieving my bag that I heard an explosion, now everyone sort of looked around and there was a moment of disbelief and bewilderment, you didn't exactly know what had happened, but a few seconds after that suddenly it went into a state of chaos.
"The sound of the explosion, the ground shook underneath my feet a bit, I mean, just, I've never heard a bomb before but there was just that sixth sense that something bad had happened."
More top news
Showers this evening then dry overnight.
Showers this evening then becoming dry but cloudy overnight.
The Prime Minister praised the armed forces as she joined celebrations in Liverpool.