A 6.6 magnitude earthquake struck central Italy, with tremors felt in Rome and Naples. The quake struck at 7.40am local time (6.40am GMT) on 30 October, the US Geological Survey said.
The epicentre was close to the town of Norcia in the province of Perugia, and 10km (6 miles) deep.
There were no immediate reports of casualties, but the disaster is reported to have caused widespread damage to structures.
The Associated Press news agency reported that nuns rushed out of their church in Norcia as the clock tower appeared about to crumble.
The US Geological Survey initially said the quake had a magnitude of 7.1, but later downgraded it to 6.6.
It comes four days after the region was struck by two earthquakes – of 5.5 and 6.1 magnitude, respectively – causing widespread damage and injuring dozens.
Norcia and nearby towns of Castelsantagelo, Preci and Visso are reported to have been largely abandoned when the latest quake struck, with many residents sleeping in cars and others moving to the coast.
Italy's civil protection department told AFP that "checks underway in all the towns affected by this morning's quake to determine whether there has been any damage to people or buildings".
Marco Rinaldi, the mayor of nearby Ussita, told the agency: "Everything collapsed. I can see columns of smoke, it's a disaster, a disaster. I was sleeping in my car, I saw hell break out."
The St Benedict basilica in Norcia is reported to have collapsed as a result of the quake, while extensive damage has been reported in Arquata del Tronto and Ussita. Tremors were felt in the Italian capital Rome and as far away as Venice.
"I was woken up by the earthquake," Rome resident Gianpaolo Giovannelli told the Guardian newspaper.
"The apartment started to shake. We feel them here in Rome, but we never get used to them, so each time we feel fear."