NORCIA, Italy (AP) -- Another powerful earthquake shook Central Italy on Sunday, sending panicked residents running into piazzas, raining boulders onto highways and toppling a Benedictine cathedral and other historic edifices that had withstood several recent quakes. There were no immediate reports of deaths.
The quake with a preliminary magnitude of 6.6 was the strongest to strike the country in nearly 36 years, hitting a mountainous region northeast of Rome where people were still unnerved after a pair of jolts last week and an August quake that killed nearly 300.
Some 20 people suffered minor injuries. That there were no reports of fatalities was largely due to the fact that thousands had left their homes after the earlier temblors.
Premier Matteo Renzi pledged that wrecked homes, churches and businesses would rise again, saying they were part of Italy's national identity. The government last week earmarked 40 million euros for rebuilding.
"We will rebuild everything," Renzi said. "We are dealing with marvelous territories, territories of beauty."
Residents already rattled by a constant trembling of the earth rushed into the streets after being roused from bed by the 7:40 a.m. quake. It was felt as far north as Salzburg, Austria, and all the way down the Italian peninsula to the Puglia region, the heel of the boot.
"It is since 1980 that we have had to deal with an earthquake of this magnitude," said Fabrizio Curcio, head of Italy's Civil Protection agency. Curcio was referring to a 6.9-magnitude quake near Naples that killed some 3,000 people and caused extensive damage in November 1980.
Curcio said authorities were responding with helicopters to help the injured and monitor collapses, as many roads were blocked by landslides. Some 3,600 people had already been relocated, many to the coast, following last week's quake, and Curcio said more would follow.
Closest to the epicenter was the ancient city of Norcia, the birthplace of St. Benedict, the father of monasticism, and famed for its Benedictine monastery. Witnesses said the 14th century St. Benedict Cathedral collapsed in the quake, with only the facade still standing.
"It's as if the whole city fell down," Norcia City Assessor Giuseppina Perla told the ANSA news agency. The city's ancient walls suffered damage, as did another famous Norcia church, St. Mary Argentea, known for its 15th century frescoes.
Television images showed nuns rushing into the main piazza as the bell tower appeared on the verge of collapse. Later, nuns and monks knelt in prayer in the main piazza. A firefighter appealed to a priest to help keep residents calm in an effort to prevent them from looking for loved ones.
The town's deputy mayor, Pierluigi Altavilla, said his house remained standing, but everything inside had been toppled.
"It seemed like a bomb exploded inside the house," he told Sky TG24.
The quake comes during a long holiday weekend in Italy ahead of Tuesday's All Saint's Day, when Catholics remember the dead. The head of the church in Umbria, Cardinal Gualtiero Bassetti, urged priests not to hold Masses inside churches but in open spaces for fear of further collapses, ANSA reported.
Mayors in some towns, including Castelsantangelo sul Nera, said coffins had been pushed out of their resting place inside cemeteries, which in Italy are typically walled structures.
"The scene is indescribable," Mayor Mauro Falcucci told ANSA.
The quake struck a cluster of mountain towns, many of historic significance, already reeling from last week's pair of aftershocks to last August's deadly quake, including Norcia, Visso, Castelsantangelo sul Nero and Preci.
Some towns and smaller settlements were left isolated by landslides that blocked the roads, and the civil protection authority was responding with helicopters to help the injured, while also monitoring damage.
A civil protection official in the Marche region, Cesare Spuri, said authorities were trying to determine if people were trapped under debris. New collapses were also reported throughout the region, including in Tolentino, where the news agency ANSA said three people were extracted from the rubble.
The hilltop town of Camerino, some 60 kilometers from Ancona, suffered new building collapses, but there were no reports of injuries. City spokesman Emmanuele Pironi said the main fire hall had been rendered uninhabitable.
Pironi said most of the area's 9,000 university students had left after the town's historic center was closed due to danger of collapses last week, and some of the 7,000 residents had been moved to hotels near the coast or to shelters nearby. Few remained in their homes.
The mayor of Ussita said a huge cloud of smoke erupted from the crumbled buildings.
"It's a disaster, a disaster!" Mayor Marco Rinaldi told ANSA. "I was sleeping in the car and I saw hell."
In Arquata del Tronto, which had been devastated by the deadly Aug. 24 earthquake, Mayor Aleandro Petrucci said, "There are no towns left."
"Everything came down," he said.
The quake sent boulders tumbling onto state highways and smaller roads, forcing closures throughout the quake zone that impeded access to hard-hit cities such as Norcia.
The Salaria highway, one of the main highways in the region, was closed at certain points. In addition, Italy's rail line said some local lines in Umbria and Le Marche were closed as a precaution.
The quake forced the temporary closure of some of Rome's most important tourist sites, including the presidential palace, so authorities could check for damage.
The St. Paul Outside the Walls basilica was closed for several hours after some plaster fell, but was later reopened. Vatican firefighters conducted checks at St. Peter's Basilica and the Vatican's other basilicas but found no damage.
The crowds in St. Peter's Square interrupted Pope Francis with applause when he mentioned the quake during his weekly Sunday blessing.
"I'm praying for the injured and the families who have suffered the most damage, as well as for rescue and first aid workers," he said.
To date, Italy's deadliest quake in recent history remains the 1908 Messina quake that destroyed the Sicilian city and killed tens of thousands of people.