Current sheets play a key role in solar flares as they are the locations where magnetic energy is liberated through reconnection and is converted to other forms. Yet, their formation and evolution during the impulsive phase of a flare remain elusive. In this talk, we will report new observations of a current-sheet formation and subsequent evolution in the early stages of a solar flare. In particular, we will present multi-phase evolution of a dynamic current sheet from its formation to quasi-stable evolution and disruption. Implications for the onset and evolution of reconnection will be discussed.