Coordinated observations of electron precipitation via x ray measurements from three simultaneously flown balloons, and of energetic particles at the geosynchronous satellite GEOS 2, were used to investigate variations of the distribution of energetic charged particles at the onset of a magnetospheric substorm onn July 3, 1979. The electron precipitation started shortly after the onset of the substorm. It was accompanied by the injection of energetic electrons and ions at GEOS 2. The intensity of the injected particles increased without any observable energy dispersion. The electron pitch angle distributions were characterized by strong intensity increases toward the geomagnetic field direction. Azimuthal anisotropies of the ion intensity around the geomagnetic field lines occurred and were interpreted as spatial density gradients. The temporal variations of the gradients indicated that a region of intense ion fluxes was located near the satellite during the period of field-aligned fluxes. It is concluded that the electron precipitation was directly related to the injection of electrons and that the injection took place well earthward of the near-earth reconnection region postulated in some substorm models. A possible mechanism that would connect injection to reconnection is proposed. The influence of parallel electric fields on the particle distribution is discussed.