http://wgno.com/2013/04/15/jfk-library-explosion-in-boston-may-be-linked-to-marathon-bombings/
Here is a clearer link to the FR April 19th post from 2010: Occult Holidays and Sabbats of April 19th http://www.freerepublic.com/focus/f-news/2496156/posts
Having taken just a cursory look, there are dozens of stories about a fire in a mechanical room at the library. Some say they heard what sounded like an explosion. Yet no one saw anything but smoke.
It sounds to me that a pump or compressor blew out.
Most people have never heard a true explosion. They would definite report the noise of an electrical or mechanical failure as an “explosion.” First reports are almost never reliable.