At least 26 people have been injured after a 4.7-magnitude earthquake rocked a region near Naples, in southern Italy.

The quake, which occurred at 7.46pm on Friday night, caused power outages, disrupted public transport and damaged a pier in Campi Flegrei, the site of Europe’s largest volcanic crater.

It is the strongest tremor to hit the region in the past 40 years and caused part of a cliff and several unoccupied buildings to collapse.

At least five of those injured were taken to hospital and about 300 people were evacuated from their homes in the city of Pozzuoli, near the epicentre of the quake, after it triggered landslides. Many residents spent the night on the streets, afraid their buildings would be damaged or collapse.

One person was only “alive by a miracle”, a rescuer told Reuters, as Italy’s civil protection minister, Nello Musumeci, urged caution and warned that the volcanic activity was not yet over.

The quake – which had a depth of 3km and was felt across Naples and the island of Ischia, and as far away as the Sorrento peninsula – was part of an ongoing seismic swarm, Italy’s national institute of geophysics and volcanology said.

After it struck, seismographs registered about 60 more tremors, with one 3.1-magnitude quake at 5.47am being felt by residents of Bacoli and Pozzuoli as well as Naples.

“There is a risk that the mountain could continue to collapse, so it is dangerous,” the rescuer said. “What makes us angry is that this situation was foreseeable, because there had already been problems with the mountain for a year and a half … The municipality knew about the situation and did nothing – perhaps if they had acted sooner, this could have been avoided.”

The heaviest damage was reported in Pozzuoli, where a building partly collapsed and large chunks of rubble crushed parked cars but did not cause any injuries.

Nine buildings have been deemed unsafe as buildings inspections continue.

“We were afraid,” one resident said. “We all ran out of our homes because it was impossible to stay inside. It lasted a long time and was very powerful, and we no longer know what we are supposed to do. We have been left here in the middle of the street, and no one has come to check on us or tell us what to do. We are here with very young children.”

Firefighters said they received reports of lifts being stuck and of a high-voltage pylon supplying electricity to the Agnano area of Naples having partly collapsed, causing disruption for 100,000 households.

The port authority said the Pozzuoli pier was unusable, and ferry and hydrofoil services to the islands had been suspended. High-speed train passengers were experiencing delays of up to six hours, with some being rerouted.