Pictures have shown the damage caused by a magnitude 4.4 earthquake which struck Naples early on Thursday, among the strongest in the area in recent history.
The quake sent 11 people to the hospital, the most serious of whom suffered concussion after part of a ceiling collapsed on them, officials said.
Some residents in Naples were forced to camp outside or sleep in their cars as the quake struck at around 1.25am (00.25am GMT), disrupting power supply in parts of the city.
In the nearby town of Pozzuoli, the ceiling of a home collapsed, seriously injuring a man who was pulled out of the rubble by firefighters, Italian newspaper Corriere Della Sera reported.
In the seaside district Bagnoli, rescuers worked to free people trapped in their homes, with some residents climbing out windows, according to news agency ANSA.
The temblor, which loosened stone and cement from some facades, was centered just offshore from Pozzuoli.
Mayor Gaetano Manfredi told reporters that one church, a seven-story residential building and another building were declared off-limits due to damage, and some schools were closed as a precaution.
Inspectors were checking buildings for further damage, Mr Manfredi said.
“We are following with the greatest attention all of our structures, and are monitoring all events in real time," the mayor said.
The quake matched the magnitude of another quake in the same area last May that has put the population on alert.
The area around the Phlegrean Fields, which encompasses western neighborhoods of Naples and its suburbs, is both seismically and volcanically active.
Authorities last summer conducted drills in preparation for a major emergency as the frequency of temblors increased.
The surface has been pushed up 1.3 meters (4.3 feet) since 2006, which is higher than prior to the last major event in 1984, but seismologists have emphasised it is impossible to predict when an eruption or stronger quake might occur.
At least 500,000 people live in the zone most at risk should the volcano erupt.
Italy's national institute for geophysics has called for a governmental plan to ensure that structures can withstand a quake of at least a magnitude 5.0.
In the 1984 event, 40,000 residents were evacuated during a period of intense seismic activity as a precaution against a feared eruption that did not occur.
