  We discuss the ICARUS T600 detector capabilities in electromagnetic shower
reconstruction through the analysis of a sample of 212 events, coming from the
2001 Pavia surface test run, of hadronic interactions leading to the production
of $\pi^{0}$ mesons. Methods of shower energy and shower direction measurements
were developed and the invariant mass of the photon pairs was reconstructed.
The ($\gamma$,$\gamma$) invariant mass was found to be consistent with the
value of the $\pi^0$ mass. The resolution of the reconstructed $\pi^0$ mass was
found to be equal to 27.3%. An improved analysis, carried out in order to clean
the full event sample from the events measured in the crowded environment,
mostly due to the trigger conditions, gave a $\pi^0$ mass resolution of 16.1%,
significantly better than the one evaluated for the full event sample. The
trigger requirement of the coincidence of at least four photomultiplier signals
favored the selection of events with a strong pile up of cosmic ray tracks and
interactions. Hence a number of candidate $\pi^0$ events were heavily
contaminated by other tracks and had to be rejected. Monte Carlo simulations of
events with $\pi^0$ production in hadronic and neutrino interactions confirmed
the validity of the shower energy and shower direction reconstruction methods
applied to the real data.
