Bombs Provide a "significant breakthrough" for London Terror Investigations

LONDON, England (CNN) -- Evidence left behind in Thursday's attempted bombings of three London Tube stations and a bus has given police what they consider to be a "significant breakthough" in their investigation.
Metropolitan Police Commissioner Ian Blair told reporters the intention of the terrorists "must have been to kill" and that some of the devices failed to explode. Police said no one needed hospital treatment after the attacks.
Blair said while the near-simultaneous attacks had echoes of ones two weeks ago that killed 52 people and the four bombers -- also on three Tube trains and a bus -- it was too early to say whether they bore the hallmarks of al Qaeda.