Slow motion footage shows the moment of the Boston Marathon bomb attack on Monday, that left three dead and over 100 wounded.<br/> <br />The usually festive event is one of the world's best known marathons, with participants hailing from all over the globe.<br/> <br />As the news spread in Britain, organizers of the London Marathon are scrutinising their own security plan.<br/> <br />But they say the London race will definitely go ahead on Sunday April 21.<br/> <br />(SOUNDBITE) (English) LONDON MARATHON CHIEF EXECUTIVE OFFICER NICK BITEL SAYING:<br/> <br />"The London marathon has a security plan which is being developed in conjunction with the Metropolitan Police. As soon as this news broke, we were in contact with our colleagues from the Met and we will as they have said, be reviewing security in the coming days with them in the light of what has happened in Boston and as more information comes out of that city as to what has actually occurred."<br/> <br />Marathon officials in Tokyo said security would be the "
