Explosion evacuates a hundred people in the Santa Monica when a bomb explodes in Chabad House. Police first announce it was not a bomb and then that it was a new kind of bomb:

Part of the confusion, authorities say, was connected to the device itself: An explosive layered under hundreds of pounds of concrete poured into a trash bin is not something bomb technicians typically encounter.

"This is clearly not a traditional type of explosive device," said FBI spokeswoman Laura Eimiller."Clearly if it were, our investigators would have been able to identify it immediately."

Thursday's blast sent a 300-pound metal pipe encased in concrete crashing through the roof of a home next door to Chabad House on 17th Street, near Broadway. Authorities are now searching for a homeless man they believe to be connected to the explosion.

Who do they blame?

A Jewish homeless person!

Can you explain to me how and where can a homeless person assemble such a weighty device?