The earthquake that struck central Italy has killed at least 247 people, the country's civil protection agency says, raising a previous count of 159.
The search for bodies is continuing through the night, authorities said.
The 6.2 magnitude earthquake has brought down buildings in central Italy, trapping residents and sending others fleeing into the streets, with many missing.
The toll was likely to rise as crews reached homes in more remote hamlets where the scenes were apocalyptic "like Dante's Inferno,'' according to one witness.
The quake struck early Wednesday (local time) and was felt across a broad swath of central Italy, including Rome, where residents felt a long swaying followed by aftershocks. The tremor shook the Lazio region and Umbria and Le Marche on the Adriatic coast.
Italian Prime Minister Matteo Renzi planned to head to the zone later on Wednesday and promised: "No family, no city, no hamlet will be left behind.'"
The hardest-hit towns were Amatrice and Accumoli near Rieti, 100km northeast of Rome, and Pescara del Tronto 25km further east. Italy's civil protection agency said the preliminary toll included several hundred injured and thousands in need of temporary housing, though it stressed the numbers were fluid.
The ANSA news agency said 35 of the dead were in Amatrice alone, with another 17 dead in the province of Ascoli Piceno, which includes Pescara del Tronto, for a reported total topping 50.
The centre of Amatrice was devastated, with entire 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,'' marvelled 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 didn't 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, too distraught to give her name. "I don't know what we'll do."
As daylight dawned, residents, civil protection workers and even priests began digging out with shovels, bulldozers and their bare hands, trying to reach survivors.
But just a few kilometres 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 90km south of the latest quake. The town sent emergency teams Wednesday to help with the rescue.
Pope Francis has dispatched one-sixth of the Vatican's tiny fire department to join rescue efforts following the earthquake that has devastated parts of central Italy.
The Vatican on Wednesday said six of its firefighters travelled to the town of Amatrice to help civil protection workers look for survivors still under the rubble and assist those already rescued.
The total force of the 108-acre city-state's fire department numbers 37.
Amatrice was one of the small mountain towns wrecked by the quake. At least 120 people have reportedly died in the disaster, with many dozens still missing.
Earlier on Wednesday, the pope cancelled a scheduled speech at his weekly general audience on religious teachings and instead prayed with the crowd for victims and survivors.
"Hearing the mayor of Amatrice say that the town no longer exists and learning that there are children among the victims, I am deeply saddened," he told tens of thousands of people gathered in St. Peter's Square.