A powerful earthquake that rocked the mountainous region of central Italy and shook much of the nation Sunday was centered in the same area rattled by a deadly quake in August and intense aftershocks last week.
Sunday's quake, the country's strongest in decades, toppled buildings in ancient towns, sent quake-weary residents into a panic and forced precautionary closure of Rome's subway system more than 100 miles away.
The magnitude-6.6 quake struck at about 7:40 a.m. local time (2:40 a.m. ET) and was centered in Norcia, a town of 5,000 people, according to the U.S. Geological Survey.
PHOTOS: Another powerful earthquake rattles central Italy
Norcia is only about 35 miles from Amatrice, a town devastated by a quake two months ago that killed nearly 300 people. The area was also hit last week by two strong aftershocks, including one measuring 6.1, that left thousands homeless.
Early reports after Sunday's temblor indicated about 20 people suffered injuries, none life-threatening, said Fabrizio Curcio, head of Italy’s civil protection agency.
"It was like an explosion that never ended," Pietro Luigi Altavilla, deputy mayor of Norcia, told Italy's ANSA news agency. "The old town was evacuated. I do not know when it will be possible to put it back together."
Marco Rinaldi, mayor of nearby Ussita, said there was severe destruction in his village of 500 people.
"Everything collapsed. I can see columns of smoke, it's a disaster, a disaster," he told ANSA. "I was sleeping in my car. I saw hell break out."
The earthquake was more powerful than the magnitude-6.2 quake that struck Italy in August, destroying parts of Amatrice and other historic towns. Many people in the region, located along a fault line, have fled to coastal towns or have been sleeping in cars or temporary shelters, afraid their homes could collapse in the night amid the continuing seismic activity.
Premier Matteo Renzi renewed his pledge to rebuild the devastated communities.
“We will rebuild everything,” Renzi said Sunday. “We are dealing with marvelous, beautiful territories.”
In Norcia, unconfirmed reports in Italian media said at least nine people were pulled alive from the rubble. Buildings were damaged and emergency workers were continuing to check for casualties. The U.S. Geological Survey said Sunday's quake was at a depth of less than a mile — a distance that is considered extremely shallow and might mean the destruction could be relatively limited.
"We are trying to learn if people are under the rubble," said Cesare Spuri, the regional head of civil protection. Later, a relieved Curcio said there was no indication anyone remained missing.
The monastery in Norcia. A picture by a friend, whose is gratefully alive. Pray to the Holy Angels! pic.twitter.com/lhabMpf3lt— Passio Jesu Christi (@PassioXP) October 30, 2016
An international community of monks in Norcia, an ancient town about 100 miles northeast of Rome known for its Benedictine monastery, tweeted an image of the 14th-century St. Benedict cathedral with only its facade standing.
"We monks are all fine, but our hearts go now to those affected," Father Benedetto, vice-prior of the monastery, told ANSA. He said monks were trying to determine whether any residents required the Catholic sacrament of extreme unction — special prayers for the sick and dying.
Strong tremors were felt as far away as Rome, where the historic Basilica of St. Paul Outside the Wall was closed for a few hours because of the appearance of large cracks in the ceiling.
Curcio said trucks of water were en route to towns affected by the quake. Helicopters were being used in areas where roads were destroyed or blocked by debris. Cardinal Gualtiero Bassetti told priests in the region to hold Mass outdoors to avoid trapping worshipers in churches if more damaging aftershocks strike. Tuesday is a holy day in the Catholic Church — All Saints Day — and churches in Italy would normally draw large crowds.
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 it later reopened. Vatican firefighters checked 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.
The last time Italy experienced an earthquake as strong as Sunday's was in 1980, when a magnitude-6.9 quake left more than 2,400 dead and injured 7,700. Tens of thousands of people lost their homes in that disaster.
Italy's Red Cross said its emergency centers were activated across the country, a common occurrence in recent weeks.
“These earthquakes are bringing all of central Italy to its knees,” Tolentino Mayor Giuseppe Pezzanesi told the Associated Press.
Contributing: Eric J. Lyman in Rome