Transit officials originally said Thursday's blasts occurred over a 26-minute span, but computer software that tracked train locations and electric circuits subsequently determined the first blast shattered the rush-hour commute at 8:50 a.m in Aldgate station, east London, with the next two erupting within 50 seconds.
A fourth explosion tore through a double-decker bus near a subway entrance, killing 13 people, nearly an hour later. The attacks hit as President Bush and other G-8 leaders were holding a summit in Scotland and a day after London was named the host city for the 2012 Olympics.
