A Fire Stopped in Reggio Emilia

It is told that on the twenty-sixth of Kislev 5446 (1686) a terrible fire broke out in the city of Reggio Emilia. A woman's nightgown, stained with her blood, was taken and hung on a house that faced the flames, and the fire died down. Rav Yitzchok, who was seven years old at the time, set the event down in Pachad Yitzchak. The article that retells it adds that some poskim regarded such a practice as a form of idolatry, and it does not rule on whether it may be used.