In a moment shall they die, and the people shall be troubled at midnight, and pass away: and the mighty shall be taken away without hand.
They - "the rich" and "princes" who offend God.
The people - namely, of the guilty princes; guilty also themselves.
At midnight - image from a night attack of an enemy on a camp, which becomes an easy prey (Exodus 12:29-30, "At midnight the Lord smote all the first-born").
Without hand - without visible agency, by the mere word of God (so Job 20:26, "a fire not blown;" Zechariah 4:6; Daniel 2:34, "a stone was cut out without hands").