Heavy rains caused several streams to overflow in the city of Livorno with officials saying that the emergency is not over.
Six people died and two were missing in the Tuscan city of Livorno after heavy rain hit the city early on Sunday, causing floods, the city's mayor said.
Between midnight and 0200 GMT, more than 250 millimetres (10 inches) of rain hit the city, causing several streams to overflow, the city of Livorno said on its website, citing several casualties.
"The emergency is not over," the administration said on the website.
"Livorno has never been so devastated by bad weather," the mayor of Livorno, Filippo Nogarin, said in a video posted on Twitter, adding the weather forecasts did not suggest a cloudburst so violent in central Italy.
Heavy rain has also hit Rome, where Mayor Virginia Raggi asked citizens to stay home.
A Serie A match between Italian soccer clubs Lazio and AC Milan, due to start at Rome's stadium at 1300 GMT, began a hour later because of the bad weather.