Scores of buildings were reduced to dusty piles of masonry in communities close to the epicentre of the pre-dawn quake, which had a magnitude of between 6.0 and 6.2, according to monitors.
It hit a remote area straddling Umbria, Marche and Lazio, to the north of a region devastated by a quake in 2009, rousing villagers and vacationers in terrifying fashion.
Italy's civil protection unit confirmed 73 fatalities in and around the villages of Amatrice, Accumoli and Arquata del Tronto.
"There's no sound from them, we only heard their cats. I wasn't here, as soon as the quake happened I rushed here. They managed to pull my sister's children out, they're in hospital now," he added, wringing his hands in anguish.
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Other victims included a nine-month-old baby girl whose parents survived.
Two boys aged four and seven were saved by their quick-thinking grandmother, who ushered them under a bed as soon as the shaking began, according to reports. She also survived but lost her husband.
"Half the village has disappeared," said Amatrice mayor Sergio Pirozzi, surveying a town centre that looked as if had been subjected to a bombing raid.
Pope Francis interrupted his weekly audience in St Peter's Square to express his shock.
"To hear the mayor of Amatrice say his village no longer exists and knowing that there are children among the victims, is very upsetting for me," he said.
Some of the worst damage was suffered by Pescara del
At least 10 bodies were recovered there.
Accumoli mayor Stefano Petrucci fought back tears as he described the scenes in his village as "a tragedy."
"There are people under the ruins, it is not a good situation."
With residents advised not to go back into their homes, temporary campsites were being established in Amatrice and Accumoli as authorities looked to find emergency accommodation for more than 2,000 people.
Amatrice is a hilltop beauty spot famed as the home of amatriciana, one of Italy's favourite pasta sauces, and is a popular destination for Romans seeking cool mountain air at the height of the summer.
Three minutes later the clock on the village's 13th-century tower stopped.
The first quake measured 6.2, according to the United States Geological Survey (USGS), which said it occurred at a shallow depth of 10 kilometres. It measured 6.0 according to Italian monitors, who put the depth at only four km.
A 5.4-magnitude aftershock followed an hour later.
Italy is often shaken by earthquakes, usually centred on the mountainous spine of the boot-shaped country.
In 2009, a 6.3-magnitude earthquake struck close to the university city of L'Aquila in the Abruzzo region and left more than 300 people dead.
David Rothery, Professor of Planetary Geosciences at Britain's Open University, said Wednesday's quake had been similar to the 2009 one.
"Both occurred at a shallow depth, which exacerbates the shaking at the surface," he said.
"Unlike the L'Aquila quake, which was preceded by swarms of smaller quakes and led to claims - unjustified in my view - that the eventual big quake should have been predicted, this one appears to have struck out of the blue.