Britain-born former Boston Marathon winner Geoff Smith has revealed that people were wandering around in shock following explosions at yesterday's event.
Two blasts near the finish line of the race caused the death of at least three people and injuries to over 100 at around 2.50pm local time.
Smith was in attendance as a spectator, but left the VIP reception to go to a restaurant and bar just before the explosions occurred.
"People were barely speaking, just saying 'Oh my God'," Smith told GoLocalProv. "Everyone was looking at the television screens at the bar. I watched for a minute and then I said to my daughter that the best thing is to get out of the city.
"We walked down Tremont Street, got in our car and got out of the city. All we could hear was sirens. About 12 ambulances went past us as we made our way to the car. Usually it's empty at this point after a marathon.
"The sad thing is that most of the people who were there are mothers, father, husbands, wives, children. They are waiting for their family members to finish the race."
The 59-year-old has won the Boston Marathon twice.