The accident happened on the cable car service between the town of Castellammare di Stabia and Monte Faito, a scenic peak offering views of the Mount Vesuvius volcano and the Bay of Naples, southeast of the city.
The car fell after a supporting cable snapped.
One of the four people killed on Thursday was a cable car operator from a nearby town, Italian media said, citing local officials.
The others were two British and one Israeli tourist, they reported.
A second Israeli tourist was in stable but critical condition, the Naples hospital treating him said on Friday.
"An unimaginable tragedy. Horrible," said Umberto De Gregorio, chairman of the EAV public transport company which runs the cable car service, on Facebook.
He said the accident was hard to explain as "all tests required by law were carried out" before the service reopened for the spring and summer season last week.
"We will have to clarify what happened."
The Monte Faito cable car offered the chance to admire "a breathtaking panorama", EAV said on its website, adding it carried 113,000 passengers in 2024.
As the supporting cable snapped, a second cabin halted in midair near the foot of the mountain, thanks to emergency brakes that are presumed to have failed to function for the car that crashed.
Prosecutors in the nearby town of Torre Annunziata were investigating the incident.
Nine people, not 16 as indicated by initial reports, were rescued from the cabin that survived, firefighters said.
Footage on RAI public television and other media showed they were evacuated one by one, with harnesses.
Fog and high winds hampered the work of emergency services, Vincenzo De Luca, head of the Campania region around Naples, told RAI.
"For Campania it was a truly tragic and painful day," he wrote on social media.
In 2021, 14 people died in Italy when a cable car linking the northern Lake Maggiore with a nearby mountain plunged to the ground.
with PA
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