Update 10.50pm: The civil protection agency has raised the death toll to 159.
Update 7pm: The death toll from the powerful earthquake in central Italy has risen to 120 people.
At least 73 people are dead and hundreds more injured after an earthquake in central Italy reduced three towns to rubble.
The death toll is likely to rise as crews reach homes in more remote hamlets where the scenes were apocalyptic, "like Dante's Inferno", according to one witness.
Complicating matters was that the area is a popular vacation spot in the summer, with populations swelling, making the number of people in the area at the time difficult to estimate.
"The town isn't here anymore," said Sergio Pirozzi, the mayor of Amatrice. "I believe the toll will rise."
The magnitude 6 quake struck at 3.36am local time and was felt across a broad swath of central Italy, including Rome, where residents woke to a long swaying followed by aftershocks. The quake shook the Lazio region and Umbria and Le Marche on the Adriatic coast.
Italy's Prime Minister Matteo Renzi planned to head to the zone later on Wednesday and promised the area, which has suffered quakes many times before: "No family, no city, no hamlet will be left behind."
The hardest-hit towns were the tiny towns of Amatrice and Accumoli near Rieti, some 80 miles north-east of Rome, and Pescara del Tronto further east.
Italy's civil protection agency, which was coordinating the rescue, said the provisional toll was 73 dead, several hundred injured and thousands in need of temporary housing.
The centre of Amatrice was devastated, with entire blocks of buildings razed and the air thick with dust and smelling strongly of gas. Amatrice, birthplace of the famed spaghetti all'amatriciana bacon-tomato pasta sauce, is made up of 69 hamlets that rescue teams were working to reach.
Rocks and metal tumbled onto the streets of the city centre and dazed residents huddled in piazzas as more than 40 aftershocks jolted the region into the early morning hours, some as strong as 5.1.
"The whole ceiling fell but did not hit me," marveled resident Maria Gianni. "I just managed to put a pillow on my head and I wasn't hit luckily, just slightly injured my leg."
Another woman, sitting in front of her destroyed home with a blanket over her shoulders, said she did not know what had become of her loved ones.
"It was one of the most beautiful towns of Italy and now there's nothing left," she said. "I don't know what we'll do."
As the August sun bared down, residents, civil protection workers and even priests dug with shovels, bulldozers and their bare hands to reach survivors. Dozens were pulled out alive: There was relief as a woman emerged on a stretcher from one building, followed by a dog.
"We need chainsaws, shears to cut iron bars, and jacks to remove beams: everything, we need everything," civil protection worker Andrea Gentili told The Associated Press. Italy's national blood drive association appealed for donations to Rieti's hospital.
But to the north, in Illica, the response was slower as residents anxiously waited for loved ones to be extracted from the rubble.
"We came out to the piazza, and it looked like Dante's Inferno," said Agostino Severo, a Rome resident visiting Illica. "People crying for help, help. Rescue workers arrived after one hour ... one and a half hours."
The devastation harked back to the 2009 quake that killed more than 300 people in and around L'Aquila, about 55 miles south of the latest quake. The town, which still has not bounced back fully, sent emergency teams on Wednesday to help with the rescue.
"I don't know what to say. We are living this immense tragedy," said a tearful Reverend Savino D'Amelio, a parish priest in Amatrice. "We are only hoping there will be the least number of victims possible and that we all have the courage to move on."
Another hard-hit town was Pescara del Tronto, in the Le Marche region, where the main road was covered in debris.
Residents were digging their neighbours out by hand since emergency crews had not yet arrived in force. Photos taken from the air by regional firefighters showed the town essentially flattened; Italy requested EU satellite images of the whole area to get the scope of the damage.
"There are broken liquor bottles all over the place," said Gino Petrucci, owner of a bar in nearby Arquata Del Tronto where he was beginning the long clean-up.
One rescue was particularly delicate as a ranger in Capodacqua, in the Marche province of Ascoli Piceno, diplomatically tried to keep an 80-year-old woman calm as she begged to get to a toilet, even though she was trapped in the rubble.
"Listen, I know it's not nice to say but if you need to pee you just do it," he said. "Now I move away a little bit and you do pee please."
The Italian geological service put the magnitude at 6.0; the US Geological Survey reported 6.2 with the epicentre at Norcia, about 105 miles north-east of Rome, and with a relatively shallow depth of 6 miles.
"Quakes with this magnitude at this depth in our territory in general create building collapses, which can result in deaths," said the head of Italy's civil protection service, Fabrizio Curcio. He added that the region is popular with tourists escaping the heat of Rome, with more residents than at other times of the year, and that a single building collapse could raise the toll significantly.
The mayor of Accumoli, Stefano Petrucci, said a family of four had died there, one of the few young families who had decided to stay in the area. He wept as he noted that the tiny hamlet of 700 swells to 2,000 in the summer months, and that he feared for the future of the town.
"I hope they don't forget us," he said.
In Amatrice, the Reverend Fabio Gammarota, priest of a nearby parish, said he had blessed seven bodies extracted so far. "One was a friend of mine," he said.
A 1997 quake killed a dozen people in central Italy and severely damaged one of the jewels of Umbria, the Basilica of St Francis in Assisi, filled with Giotto frescoes. The Franciscan friars who are the custodians of the basilica reported no immediate damage from Wednesday's temblor.
Pope Francis skipped his traditional catechism for his Wednesday general audience and instead invited pilgrims in St Peter's Square to recite the rosary with him.