An incident in Žirmūnai's history that has been difficult to reconstruct occurred in 1975, when a pontoon bridge across the River Neris, that was customarily set up from spring to autumn, collapsed due to the weight of a crowd returning from a concert in the Palace of Concerts and Sports. It was rumoured that the bridge supports were not fully connected at the time. There were witnessed fatalities involving drownings and crushing by the bridge structures. Public discussion of the disaster was restricted and the number of casualties remains unknown. The pontoon bridge was never re-erected at the site; the Mindaugas Bridge now serves this need.