Yemeni officials have detained a female medical student in her 20s who is suspected of sending explosive to the U.S. on cargo planes. The hunt is also on for Ibrahim Hassan al-Asiri, a 28-year-old bomb mastermind working with al Qaeda's Yemen branch. Asiri is linked to both this plot and last year's failed Christmas Day underwear bomber attack. British officials believe the bomb intercepted in the U.K. was meant to explode on the plane—and was viable to do so. Janet Napolitano, the U.S. homeland security secretary, linked the plot to al Qaeda, telling ABC news Saturday morning that the intercepted packages contained PETN, one of the "hallmarks" of the group.