It doesn't appear to have been anything major, just a small electrical fire on the 12th floor, however two people were injured and taken to MGH and one poor fellow lost his dignity and his pants as you will see on the globe's site. I took a walk by here around 12:50 after lunch and it looked like half the city's fire department was there, which naturally made things look a lot worse.
http://www.boston.com/news/local/breaking_news/2008/04/electrical_fire.html
http://www.boston.com/news/local/breaking_news/2008/04/electrical_fire.html