London spectators have spoken about their "determination" to attend this years Marathon- despite events in Boston.
Three people were killed after two brothers detonated bombs at the end of the Boston Marathon.
London competitors observed a 30-second silence, as they paid their respects to those affected by Monday's incident.
Thousands of runners wore black ribbons in a show of solidarity with the US city.
Margaret McKinlay, 61, from Edinburgh, said she believed what happened in Boston made people particularly keen to see the Marathon for themselves.
"If anything it made me more determined. What happened in Boston was particular to there.
"I think people would be more determined to do it than anything," she said.
Jay Blatnik, 26, from Wisconsin, said he did not know anyone taking part in the marathon, but wanted to come to see it regardless - and events in Boston were not going to stop him.
"It didn't cross my mind about not coming. Maybe in the back of my mind I thought 'I'm not afraid of coming out. It's not scaring me away'.
"I can't even imagine what that was like.
"I assume it was like this atmosphere and then in an instant it changed.
"Not only from the spectators' point of view but also the runners' point of view," he said.
Hugh Elder, 64, said he had witnessed an IRA bomb close to where he was standing.
"I've lived in London for 40 years. I've been blown up by the IRA.
"I wasn't hurt but I was knocked off my feet, so a couple of teenagers in Boston aren't going to affect me," he said.