In the Tokapole II tokamak [Nucl. Fusion19, 1509 (1979)] the three‐dimensional structure of the rapid sawtooth crash that accompanies internal disruptions has been observed. The sawtooth crash is helical, i.e., the decrease in soft x‐ray intensity occurs along aq=1 helical contour, in accord with the standard reconnection model. The poloidally asymmetric radial expansion of the crash inward from theq=1 surface provides a measure of the reconnection time consistent with single helicity reconnection from a growing, nonrotating magnetic island.