Judging from what is coming out at the moment, it was designed for many casualties.
Ah, well wouldn't be the first time I was wrong. I haven't been following it except for the headlines. They caught me on a day where I really don't feel up to reading through CNN's [garbage].

I'm curious then as to why it was packed in nails. With a large explosion you'd generate enough of your own pressure/shrapnel, I would think. I guess when trying to kill as many as possible there's no such thing as "overkill".

Fortunately for Londoner's, there is a such thing as "underkill".