Here’s the Boston.com live blog.

I don’t plan to speculate about who the perpetrators behind this tragedy might be. Until or unless someone claims responsibility it’s going to be up to the forensics teams to figure it out. We also know that all initial reports are just that: initial. It takes time to uncover facts. So I’m content to wait for the professionals to sort it out.

You should read Charlie Pierce’s reporting from the scene. How anyone can paint a picture so well in such a short time astonishes me.