I saw it on the news and the police spokes man said that there were nails found near the source. It is appalling that they were targeted at all.

Err... what? You mean like holding together the bench it was left on?

I was thinking more like a pile of nails next to a banger. Though it sounds like they were in a bomb of some sort so it does look like it was intended to harm. It might have been that the bomb was not as effective as planned so that probably saved lives.