DHS: No Evidence of a Broader Bomb Plot

But will maintain more security at transportation centers for now

Homeland Security Secretary Janet Napolitano says there is no evidence that the bombings at the Boston Marathon are part of a wider plot.

Napolitano says DHS will maintain what she called "enhanced security measures at transportation hubs" as a precaution.

Two people briefed on the investigation tell The Associated Press that a pair of bombs packed into pressure cookers and concealed in duffel bags blew up within seconds of each other.