VATICAN CITY, August 24 (Reuters) - Pope Francis, saddened by an earthquake that struck central Italy overnight, on Wednesday cancelled a speech he was to have given at his general audience and instead prayed with the crowd for victims and survivors. "Hearing the mayor of Amatrice say that the town no longer exists and hearing that there are children among the victims, I am deeply saddened," he told tens of thousands of people who had gathered in St. Peter's Square for his general audience.