  Using data collected at the Pierre Auger Observatory during the past 3.7
years, we demonstrated a correlation between the arrival directions of cosmic
rays with energy above ~ 6x10^{19} electron volts and the positions of active
galactic nuclei (AGN) lying within ~ 75 megaparsecs. We rejected the hypothesis
of an isotropic distribution of these cosmic rays with at least a 99%
confidence level from a prescribed a priori test. The correlation we observed
is compatible with the hypothesis that the highest energy particles originate
from nearby extragalactic sources whose flux has not been substantially reduced
by interaction with the cosmic background radiation. AGN or objects having a
similar spatial distribution are possible sources.
