At least two people were killed and 110 injured in Boston, Mass. today (April 15) when two bombs were detonated near the finish line during the running of the annual Boston Marathon.

According to CNN, Federal authorities have classified these events as a terrorist attack, and conflicting reports indicate other explosive devices have been found around the city. As the story continues to unfold on national news, musicians took to Twitter to share their shock, grief and prayers for the those hurt or affected by this senseless tragedy: