22 or more people have been injured, and 2-3 or more have been killed by what appears to be some form of coordinated attack on the Boston Marathon, according to live police scanner updates.
Boston police have confirmed via their live scanner that an additional detonation occurred at the John F. Kennedy Presidential Library, also in Boston. It is currently unclear whether there were any casualties at that location.
An additional explosive device was reported outside of Boston's Mandarin Oriental Hotel. If that report was accurate, it appears that said device is in the process of, or has already been, destroyed by Boston Police Department explosives experts.