Aims. We search for direct evidence of ongoing star formation by accretion in the Lagoon Nebula (M 8), using optical wide-field narrow-band imaging obtained at La Silla Observatory. Methods. We examine [S II] and Hα images for line-emission features that could be interpreted as signatures of outflow activity of the exciting sources. Results. We discover five new Herbig-Haro objects, study in detail their morphology and attempt to identify their potential driving sources among the population of T Tauri stars and embedded sources in the surroundings. Conclusions. The results reported here conclusively demonstrate the existence of very young stars going through the accreting phase in the M 8 region.Instituto de Astrofísica de La PlataFacultad de Ciencias Astronómicas y Geofísica
