AMATRICE, Italy — A powerful temblor early Wednesday, Italy's deadliest in nearly a decade, devastated a string of picturesque villages nestled in the Apennine Mountains, killing at least 159 people and injuring hundreds. It left thousands homeless and others missing as rescuers scoured the rubble for signs of life.

“It was a ‘boom' — but it was noise you felt through your bones, rather than heard,” said 19-year-old student Alessio Serrafini, sitting on a park bench in the town of Amatrice, about 85 miles northeast of Rome, recounting the moment when the quake hit.

Survivors, some of them having escaped only in underwear or pajamas, spent hours outdoors, first huddling in blankets in the predawn chill, then sweltering in the afternoon heat.

Italian emergency personnel set up shelters and urged quake victims to come away and try to rest, but many remained glued to the scene of collapsed structures, where the sound of heavy equipment and the shouts of rescuers echoed into the evening.

Village clocks stopped when the initial jolt hit — at 3:36 a.m. — and aerial photographs showed the scope of devastation, gray dust and piles of masonry replacing what had been quaint medieval streets and piazzas.

Onlookers made the sign of the cross as rescuers pulled bodies from the rubble, loading them onto doors and planks that served as makeshift stretchers. “There will be a lot more coming,” Father Savino D'Amelio, a parish priest, said sadly as he walked among the dead.

Ten hours after the quake, two small children were pulled still breathing from the ruins of a house in Amatrice — one an infant, the other a toddler.

Amatrice, consisting of a small town center surrounded by dozens of hamlets, draws visitors ranging from well-to-do Romans who own vacation homes to backpackers and young revelers from across Europe, all enjoying the waning days of summer. This weekend, the town was to have held an exuberant annual festival in honor of the pasta dish named for it, spaghetti all'Amatriciana.

At the Vatican, Pope Francis led pilgrims in St. Peter's Square in prayer for the victims. European governments offered condolences, and President Barack Obama telephoned Italy's president to offer thoughts and prayers, as well as any needed assistance. The Italian government mobilized troops to help with rescue efforts and quickly freed up emergency funds for disaster relief.

Cultural treasures fell victim as well. Officials were assessing the damage to landmark churches, paintings and frescoes, including the cracked fourth century facade of the Basilica of St. Francis and the 15th century Church of St. Augustine, next to Amatrice's ancient walls, the Ansa news agency reported.

Residents told of narrow escapes — and desperate efforts to save others. When the quake hit, student Alex Ciccone said, he was not in bed like most people; he was escorting home a friend who had had too much to drink.

The 21-year-old quickly joined in the initial rescue effort, groping his way through debris-choked streets. “The world was white with dust,” he said. Hours later, he learned that two good friends were among those killed in the quake.

Prime Minister Matteo Renzi visited the quake zone and promised that his Cabinet would enact speedy measures to spur reconstruction. Earlier, in a brief nationwide televised address, he pledged aid and solidarity for the victims.

“No one will be left alone — no family, no community, no neighborhood,” he said.

In Amatrice, the hospital was among the damaged buildings, so medical workers quickly moved patients outdoors, and then began treating arriving injured in the open air.

Pasquale Carducci, the hospital director, helped evacuate bedridden patients, still hooked up to their intravenous drips.

“Amatrice is finished,” he said.

The quake's epicenter was relatively shallow, magnifying its destructive power. The U.S. Geological Survey put the magnitude at 6.2, while Italy's geological observatory measured it at magnitude 6.0.

The temblor had jolted people awake in Rome, setting off car alarms and knocking books from shelves, and was felt as far away as Naples, some 200 miles away in the country's south.

In seismically active Italy, the last major earthquake was in 2009, in the central city of L'Aquila, about 50 miles south of Wednesday's quake zone. It killed more than 300 people.

In the hours after the quake, priests moved through the devastated area, seeking to provide comfort even if they were in tears themselves. One cleric told of blessing bodies pulled from the wreckage — including that of a friend.

Los Angeles Times special correspondent Tom Kington reported from Amatrice, Italy, and staff writer Laura King from Washington.

laura.king@latimes.com