A crane standing about 15 stories high toppled at a construction site and smashed into a block of apartment buildings Saturday, killing at least two people, authorities said. The collapsing crane demolished parts of several buildings on Manhattan's East Side and appeared to have pulverized one small, brick apartment building. Fire Department officials said at least two people were dead. A rescue operation was under way and it was unclear whether anyone was trapped in the rubble. Nearby residents reported hearing a terrible roar as the structure detached from a large building under construction.