In the early morning, a wave of mud and debris devastated the small town of Casamicciola Terme in the north of the island, submerging at least one house and carrying cars towards the sea, according to Italian media and the emergency services. .
The first victim is a woman whose body was found by rescuers, announced the prefect of Naples, Claudio Palomba, during a press conference.
Some of those initially missing were later found safe and sound, including a family with a newborn baby, the prefect said. But there was no news of a dozen people in the middle of the afternoon, according to Mr. Palomba.
Search operations are complicated by persistent rain and strong winds, which have also delayed the delivery of reinforcements by ferry from the mainland.
Italian Interior Minister Matteo Piantedosi earlier said several people were stuck in the mud, citing a "very serious" situation.
He had nevertheless denied the assertions of his colleague, the Deputy Prime Minister and Minister of Infrastructure Matteo Salvini, who had given a death toll of eight.
"At this precise moment, no death has been confirmed," added Mr. Piantedosi, while pointing out that the situation could still evolve.
- Complicated rescue -
Casamicciola Terme, a spa resort of 8,000 inhabitants in winter on the lush island of Ischia, near Capri, suffered an earthquake in 2017 that killed two people. It had, however, been completely destroyed by a much more powerful earthquake at the end of the 19th century.
The landslide sent torrents of mud onto the streets which overturned trees and swept away and dented vehicles there, sometimes to the sea, according to images from the emergency services and local media.
The landslide "buried a house" and two people were rescued from a car that had been thrown into the sea, the fire department said.
At least 30 families are trapped in their homes by mud, without water or electricity, ANSA news agency said, adding that the road leading to their neighborhood was cut off by the mudslide and debris.
The emergency services then explained that they hoped to evacuate 150 to 200 people by Saturday evening to temporary accommodation.
"Rescue operations remain complicated because of the weather conditions," according to the civil protection department, but the search will continue throughout the night thanks to searchlights.
The local authorities have called on the inhabitants of the island to stay at home, so as not to interfere with the rescue operations.
Prime Minister Giorgia Meloni said she was following the situation, offering her thoughts to those affected by the disaster.
This comes a few weeks after the death of 11 people in floods due to heavy rains in central-eastern Italy.