( CNN ) -- Two days after London Marathon bombings , thousands of runners will compete in London . Special event marked by 30 second silence , black mourning flag . Stepped - up security with increased searches and police on site . Olympics 2012 good training ground for staging international sporting events .
Two days after London Marathon bombings , thousands of runners will compete in London . Special event marked by 30 second silence , black mourning flag . Stepped - up security with increased searches and police on site . Olympics 2012 good training ground for staging international sporting events .