STORY: Torrential rain hit the port of Casamicciola Terme, one of the six small towns on the island, in the early hours, triggering flooding and bringing down buildings.
"Currently the confirmed death toll is one, a woman. Eight missing persons have been found, including a child, and there still are around 10 missing," the prefect of Naples, Claudio Palomba, told a news conference.
Infrastructure Minister Matteo Salvini said earlier during an event in Milan that eight people had been killed.
Seventy firefighters are working on the island, which lies some 30 km (19 miles) from Naples, to rescue residents from damaged buildings and search for missing persons, Italy's fire brigade said on Twitter.