A powerful earthquake devastated a string of mountain towns in central Italy on Wednesday, trapping residents under rubble, killing at least 73 people and leaving thousands homeless.

The quake struck in the early hours of the morning when most residents were asleep, razing homes and buckling roads in a cluster of communities some 140 km (85 miles) east of Rome. It was powerful enough to be felt in Bologna to the north and Naples to the south, each more than 220 km from the epicenter.

A family of four, including two boys aged 8 months and 9 years, were buried when their house in Accumoli imploded.

As rescue workers carried away the body of the infant, carefully covered by a small blanket, the children's grandmother blamed God: "He took them all at once," she wailed.

The army was mobilised to help with special heavy equipment and the treasury released 235 million euros ($265 million) of emergency funds. At the Vatican, Pope Francis canceled part of his general audience to pray for the victims.

Rescue workers used helicopters to pluck trapped survivors to safety in the more isolated villages, which had been cut off by landslides and rubble.

Aerial photographs showed whole areas of Amatrice, voted last year as one of Italy's most beautiful historic towns, flattened by the 6.2 magnitude quake. Many of those killed or missing were visitors.

"It's all young people here, it's holiday season, the town festival was to have been held the day after tomorrow so lots of people came for that," said Amatrice resident Giancarlo, sitting in the road wearing just his underwear.

"It's terrible, I'm 65-years-old and I have never experienced anything like this, small tremors, yes, but nothing this big. This is a catastrophe," he said.

The national Civil Protection Department gave the official death toll of 73 at about 12 hours after the pre-dawn quake struck. Scores more will still believed unaccounted for, with the presence of the summer holidaymakers making it difficult to tally.

Disappearing into dust

Patients at the badly damaged hospital in Amatrice were moved into the streets.

"Three quarters of the town is not there anymore," Amatrice mayor Sergio Pirozzi told state broadcaster RAI. "The aim now is to save as many lives as possible. There are voices under the rubble, we have to save the people there."

Stefano Petrucci, mayor of nearby Accumoli, said some 2,500 people were left homeless in the local community, made up of 17 hamlets.

Residents responding to wails muffled by tonnes of bricks and mortar sifted through the rubble with their bare hands before emergency services arrived with earth-moving equipment and sniffer dogs. Wide cracks had appeared like open wounds on the buildings that were still standing.

The national Civil Protection Department said some survivors would be put up elsewhere in central Italy, while others would be housed in tents that were being dispatched to the area.

Prime Minister Matteo Renzi said he would visit the disaster area later in the day: "No one will be left alone, no family, no community, no neighborhood. We must get down to work .. to restore hope to this area which has been so badly hit," he said in a brief televised address.

A spokeswoman for the civil protection department, Immacolata Postiglione, said the dead were in Amatrice, Accumoli and other villages including Pescara del Tronto and Arquata del Tronto.

Most of the damage was in the Lazio and Marche regions. Neighboring Umbria was also affected.

The US Geological Survey, which measured the quake at 6.2 magnitude, said it struck near the Umbrian city of Norcia, while Italy's earthquake institute INGV registered it at 6.0 and put the epicenter further south, closer to Accumoli and Amatrice.

INGV reported 150 aftershocks in the 12 hours following the initial quake, the strongest measuring 5.5.

The damage was made more severe because the epicenter was at a relatively shallow 4 km below the surface of the earth. Residents of Rome were woken by the tremors, which rattled furniture, swayed lights and set off car alarms in most of central Italy.

"It was so strong. It seemed the bed was walking across the room by itself with us on it," Lina Mercantini of Ceselli, Umbria, about 75 km away from the hardest hit area, told Reuters.

Italy sits on two fault lines, making it one of the most seismically active countries in Europe.

The last major earthquake to hit the country struck the central city of L'Aquila in 2009, killing more than 300 people.

The most deadly since the start of the 20th century came in 1908, when an earthquake followed by a tsunami killed an estimated 80,000 people in the southern regions of Reggio Calabria and Sicily.