A typical flare--coronal mass ejection (CME) event is studied at the initial time and position of the flare and CME. The photospheric magnetic configuration consists of two main polarities (dipolar structure) with some emerged new polarities, similar to a quadrupolar structure, during the event. The coronal loops in soft X-ray and EUV images show the signature of the loop interaction, i.e., the storage of the magnetic energy. The radio bursts at 1--2 GHz were observed with fast frequency drifts with bidirectional drift pairs, which may provide a direct signature of upward and downward particle acceleration from the reconnection site, followed by the bulk energy release of the flare. After that, the soft X-ray and EUV loops were suddenly opened and closed again in 10 min. The open time is around the maximum phase of the flare as well as the start time of the associated CME. Meanwhile, the polarization sense of the microwave bursts suddenly reversed at 2.6--3.8 GHz, which might have been caused by the fast variation of coronal loops or the magnetic field. The high-time-resolution (8 ms) data show the microwave bursts at 2.6--3.8 GHz, with slow frequency drifts and zebra structures in the initial phase of the CMEs or shock formation. Hence it is suggested that flares and CMEs may be triggered simultaneously by some MHD instabilities or by reconnection in a favorable magnetic configuration to release the free magnetic energy in two different ways.