Did the government set explosives in the World Trade Center buildings 1,2 and 7 and take them down on 9/11?

I have serious reservations over whether a government would risk attacking its own people in order to justify their war efforts. To me, the weight of the buildings coupled with the melted metal would of led to the sliding motion you witnessed. Had there been a bomb, there would of been a sonicboom blast following it which would of been heard at ground level for several miles, there was not.