We report for the first time that the dynamic magnetic intermediate state (DMI) was observed at a speed of several ns during spin transfer switching for MgO-based magnetic tunnel junctions (MTJs). The DMI was observed as slow resistance oscillation at the center of the parallel to anti-parallel state by single shot time domain measurements. The DMI is observable at certain current amplitudes. The outbreak probability decreases with further current increase. We concluded that the DMI originates from inhomogeneous magnetization behavior. On the other hand, previous single shot time domain measurements have shown only for single-domain-like magnetization behavior.