A pair of powerful aftershocks have shaken central Italy just two months after an earthquake killed nearly 300 people.
The first quake carried a magnitude of 5.4, but the second one was even stronger, with a preliminary magnitude of 6.1 according to the German Research Centre for Geosciences.
The US Geological survey put the magnitude at 6.0 and said the epicentre was in Visso, where buildings crumbled into the street.
People screamed in the streets after the second temblor of the night. "It was a very strong earthquake, apocalyptic," Ussita Mayor Marco Rinaldi told the ANSA news agency. "People are screaming on the street and now we are without lights."
Two people were injured in the Visso area, but otherwise there were no other immediate reports of victims, said Italy's civil protection chief, Fabrizio Curcio.
Old churches crumbled and other buildings were damaged, though many of them were in zones that were declared off-limits after the quake on August 24 that flattened parts of three towns.
"We're without power, waiting for emergency crews," said Mauro Falcucci, the mayor of Castelsantangelo sul Nera, near the epicentre. He said: "We can't see anything. It's tough. Really tough."
He said some buildings had collapsed, but that there were no immediate reports of injuries in his community.
Italy's national vulcanology centre said the first quake struck at 7.10pm local time with an epicentre in the Macerata area, near Perugia in the quake-prone Apennine Mountain chain. The US Geological Survey put the epicentre near Visso and said it had a depth of six miles.
The second aftershock struck two hours later at 9.18pm with a similar depth.
Experts say even relatively modest quakes that have shallow depths can cause significant damage because the seismic waves are closer to the surface. But seismologist Gianluca Valensise said a six-mile depth is within the norm for an Apennine temblor.
The August 24 quake destroyed the hilltop village of Amatrice and other nearby towns and had a depth of about six miles. Amatrice Mayor Sergio Pirozzi said residents felt the aftershocks but "are thanking God that there are no dead and no injured".
Wednesday's temblors were felt from Perugia in Umbria to the capital Rome to the central Italian town of L'Aquila, which was struck by a deadly quake in 2009. The mayor of L'Aquila, however, said there were no immediate reports of damage there.
A section of a major state highway north of Rome, the Salaria, was closed near Arquata del Tronto as a precaution because of a quake-induced landslide, said a spokeswoman for the civil protection agency, Ornella De Luca.
The mayor of Arquata del Tronco, Aleandro Petrucci, said the aftershocks felt stronger than the August quake, which devastated parts of his town. But he said there were no reports of injuries to date and that the zone hardest hit by the last quake remained uninhabitable.
"We don't worry because there is no one in the red zone, if something fell, walls fell," he said.
In Rome, some 145 miles south-west from the epicentre, centuries-old palazzi shook and officials at the Foreign Ministry evacuated the building.
The quakes were actually aftershocks of the magnitude 6.2 earthquake from two months ago. Because they were so close to the surface, it has the potential to cause more shaking and more damage, "coupled with infrastructure that's vulnerable to shaking," said US Geological Survey seismologist Paul Earle.
"They have a lot of old buildings that weren't constructed at a time with modern seismic codes," he said.
Given the size, depth and location of the quakes, the USGS estimates that about 12 million people likely felt at least weak shaking.
This original quake was about 12 miles north-west of the original shock, which puts it on the northern edge of the aftershock sequence and two months is normal for aftershocks, Mr Earle said. The August 6.2 quake was five times bigger than Wednesday's and was 11 times stronger based on energy released.