Footage showed water streaming down streets in Catania, a city on the eastern side of the Italian island which has been badly-hit by the floods.
Cars were seen submerged by water and debris littered the streets after torrential rain battered the city.
According to the mayor, Catania has experienced its average yearly rainfall in just 48 hours.
A spokesperson for the Misericordie group of volunteers said a body of a man had been found under a car in the town of Gravina, north of Catania, amid the flooding. Local media reported he was 53 years old.
On Monday, a 67-year-old man died after his car was hit by rising waters and mud. Rescue teams said they were searching for his wife, who is missing.
The rain has inundated some of Catania’s most famous streets and squares, causing a blackout in the city centre and flooding shops.
“Since yesterday, our city has been experiencing a tragic situation linked to weather conditions that are battering the whole of Sicily’s eastern side,” Catania’s mayor, Salvo Pogliese, wrote on Facebook on Tuesday.
He said events were “unprecendented” due to their “force and intensity”.
“I urge everyone to not leave their homes unless it is for reasons deemed an emergency, as water has flooded the roads,” the major added.
Mr Pogliese ordered Catania’s schools to close Tuesday and Wednesday due to the bad weather.
On Tuesday afternoon, he said “all commercial activity” had to stop until midnight on Wednesday “due to the seriousness of the situation”.
Meanwhile, a fire service spokesperson said: “The emergency situation is widespread and extremely critical and it does not seem to be improving.”
Italian weather site Ilmeteo.it said parts of Sicily and the adjacent toe of Italy, Calabria, were being pounded by a rare tropical-like cyclone known as a medicane, and the sea was 8C warmer than the average for this time of year.
It has forecast rain to continue throughout the rest of the week.
Additional reporting by Reuters
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