The quakes, all measuring more than five magnitude, struck close to Amatrice, the mountain town devastated by an August earthquake that left 299 people dead.
AS IT HAPPENED: The Local's live blog on the earthquakes
The body of one victim was found under the debris of a building in the town of Castel Castagna, in the province of Teramo, local authorities said in a statement. And at least three more people were missing having been swept away in an avalanche, rescuers were reported as saying by local media.
They had been among around 20 tourists staying at a hotel in the province of Pescara, which four rescue teams are now trying to reach amid difficult conditions.
And as night fell and temperatures plummeted, fears mounted for isolated residents of remote hamlets cut off by heavy snowfall, while more than 130,000 homes were without electricity.
A mother and child dragged from the ruins of a collapsed country cottage near Teramo in the Abruzzo region were both found to be suffering from hypothermia.
Shortly before dusk, Nello Patrizi, a farmer in Montereale, south of Amatrice, was out with his dog, trying to check on cows knee-deep in snow.
"It was an apocalyptic shock. We were petrified," the 63-year-old told AFP. "The first one was bad enough, the others seemed even stronger. You had the impression everything was collapsing, people were screaming.
"With all the snow there was this morning, people could not get out of their houses. I thought 'all we need now is an earthquake' and here it is."
A night under canvas
Fabio di Gianfrancesco, 55, drove from Rome to another hamlet, Aringo, to check on elderly relatives. "They were trapped in the house because of the snow," he said. "We got them out and then helped the last ten or so residents here to leave."
Around 160 people were preparing to spend the night under the canvas of a giant tent on a local sports field.
Residents prepare the makeshift shelter. Photo: Andreas Solaro/AFP
Wednesday's first shock struck at 10:25 am (0925 GMT). Monitors put its strength at between 5.1 and 5.3 magnitude. A second, 50 minutes later, was measured between 5.4 and 5.7.
A third, minutes later, measured 5.3, while one of more than 100 major aftershocks was measured at 5.1 at 2.30 pm.
IN PICTURES: 24 hours in Montereale after four major quakes
The tremors were felt powerfully across the Abruzzo, Lazio and Marche regions and clearly in Rome, over 100 kilometres (60 miles) away.
Residents of Aquila, where over 300 people died in a 2009 earthquake, rushed into the snow-covered streets in panic but the city suffered little damage.
Avalanche warnings were issued across a region that has a number of ski resorts and a highest peak, Gran Sasso, at 2,912 metres (9,554 feet).
A high-risk country
In Amatrice, the belltower of the 15th Century Church of Sant'Agostino collapsed. It had been damaged by the first of the earthquakes which struck the mountainous centre of the country between August and October last year.
Most of those who died in that quake were in the town, a beauty spot which was packed with holidaymakers at the height of the summer season.
Two further quakes rattled the region in October, with the most powerful measuring 6.5 magnitude.
Amatrice mayor Sergio Pirozzi cursed his town's bad luck.
"I don't know if we did something bad. That's what I have been asking since yesterday. We have got up to two metres of snow and now another earthquake!"
Stefano Petrucci, mayor of nearby Accumoli, said roads were unpassable and bemoaned a shortage of clearance trucks. "We can't fight a war with bows and arrows."
The affected area is thinly populated and thousands of residents were evacuated last year pending reconstruction of their homes.
The last of the 2016 quakes, on October 30th, was the most powerful since a 6.9 magnitude one struck near Naples in southern Italy in 1980, leaving 3,000 people dead.
Much of the country's land mass and some of its surrounding waters are prone to seismic activity with the highest risk concentrated along its mountainous central spine.
Italy straddles the Eurasian and African tectonic plates, making it vulnerable when they move.
The worst disaster of the 20th century was in 1908 when an estimated 95,000 died in tidal waves following a quake in the sea between mainland Italy and Sicily.
By Ella Ide with Angus MacKinnon in Rome