Extra security as London marathon goes ahead Hundreds of extra police officers are on duty at the London Marathon following the Boston bombings. More than 35,000 runners will pound the streets of London wearing black ribbons. A 30-second silence will be observed in memory of last Monday's victims: "I think you always worry a lot about the security, especially just after Boston, but I think you've got to keep on going," said one competitor: Authorities say more search dogs will be deployed and urged those attending the event to keep their belongings close to avoid any unnecessary security alerts. Organisers claim the build up to the event has passed off smoothly and everyone is expecting a fantastic day. More about: London, Marathon, Terrorism, United Kingdom