We report on the X-ray emission from the shell-like, non-thermal radio source Sgr A East (SNR 000.0+00.0). The X-ray emitting region is concentrated within the central ~=2 pc of the larger radio shell. The spectrum shows strong Kα lines from highly ionized ions of S, Ar, Ca, and Fe. The plasma appears to be rich in heavy elements, over-abundant by roughly a factor of four with respect to solar abundances, and shows a spatial gradient of elemental abundance: the spatial distribution of iron is more compact than that of the lighter elements. The X-ray properties support the long-standing hypothesis that Sgr A East is an old supernova remnant (SNR). .