>> from the underground, that radical left wing group, the weathermen promises more attacks on the establishment around the entire country starting next week. the medium for this message was a tape recording reputedly by the weatherman rebel leader, bernadine donor. >> sisters and brothers, we are not just attacking targets. we are bringing a pitiful, helpless giant do their knees. guard your children, guard your doors. >> at one minute before 1:00 this morning, the switchboard at the capitol received a phone call. a man's voice said a bomb would go off in the building in half an hour. at 1:30 in the morning it did. credit for the bombing was claimed by the weather underground. >> in 1971, it appears that weather is really aiming even higher. and at that point, their idea was fewer bombs, higher profile targets. >> weather underground bomb the capitol to bring joy, to bring joy to america, to bring a smile