NEW : ` ` We want to reassure runners , spectators , volunteers '' about safety , says event CEO . ` Our immediate thoughts are with all the people there and their families . Organizers of Buckingham Palace say it will take place as planned each year . Britain mayor says `` robust security measures '' are in place for the event . two of people take part in the race Sunday , cheered on by many more .
NEW : `` We want to reassure runners , spectators , volunteers '' about safety , says event CEO . Organizers of Buckingham Palace say it will take place as planned each year . Britain mayor says `` robust security measures '' are in place for the event . two of people take part in the race Sunday , cheered on by many more .