The reaction pd → π - ppp has been investigated in a line-reversed hydrogen bubble chamber experiment using 3.3 GeV / c deuteron beam. The present work appears to be the first account of this reaction in the GeV region. The observed spectra are very well reproduced by a parameter-free calculational scheme based on the impulse approximation and one-pion-exchange model of pion production. Our approach is fully relativistic and special care has been taken to ensure the proper antisymmetry of the three-proton states. When kinematical cuts are introduced to suppress the dominant quasi-free pion-production processes, the effective mass distributions exhibit narrow enhancements which are not accounted for by our model and might be considered as candidates for dibaryonic resonances.