One of the blasts (at least) was in the Piccadilly Line -- under King's Cross. The Piccadilly Line runs deep, very deep, too deep it is said for cell phones to work. That means the bomb was probably detonated by a person or persons. Except there is some speculation as to whether it could have been detonated remotely by another stronger piece of communications technology. That according to a report about an hour ago on the BBC.