NEW : Double winner of women 's wheelchair race dedicates her victory to Boston victims . Score: 6 Supporters voice solidarity with Boston as they cheer on the London runners . Chief Supt . Runners joined a 30-second start-line silence in tribute to the Boston bombing . Security is ramped up for the event , with more police on the streets .
NEW : Double winner of women 's wheelchair race dedicates her victory to Boston victims . Score: 6 Supporters voice solidarity with Boston as they cheer on the London runners . Runners joined a 30-second start-line silence in tribute to the Boston bombing . Security is ramped up for the event , with more police on the streets .