With 368 people injured, some critically, and an unknown number trapped under rubble, the death toll from the pre-dawn quake was expected to rise further, officials warned on Wednesday.
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Amid scenes of carnage, dozens of emergency services staff and volunteers were preparing to work through the night in the hope of plucking more survivors from the ruins. The rescue efforts "won't slow down during the night", the head of the civil protection agency Fabrizio Curcio told public broadcaster Rai, giving an updated toll of 159 dead.
He did not say how many people were still thought to be missing. Prime Minister Matteo Renzi had earlier said at least 120 people were killed in the earthquake. "This is not a final toll," he had warned after visiting the badly hit village of Amatrice.
Hundreds of people were to spend a chilly night in hastily assembled tents with the risk of aftershocks making it too risky for them to return home. Scores of buildings were reduced to dusty piles of masonry in communities close to the epicentre of the quake, which had a magnitude of between 6.0 and 6.2.
It hit a remote area straddling Umbria, Marche and Lazio at a time of year when second-home owners and other visitors swell the numbers staying there. Many of the victims were from Rome.
The devastated area is just north of L'Aquila, the city where some 300 people died in another quake in 2009. Most of the deaths occurred in and around the villages of Amatrice, Accumoli and Arquata del Tronto.
Guido Bordo, 69, lost his sister and her husband after they were trapped inside their holiday house in the hamlet of Illica, near Accumoli. "There's no sound from them, we only heard their cats," he told AFP before the deaths were confirmed.
"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.
Among the victims was a nine-month-old baby girl whose parents survived, an 18-month-old toddler and two other young children who died with their parents in Accumoli.
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.