A magnitude 6.2 earthquake has struck central Italy, leaving at least 37 people dead and 150 missing, as rescuers search for survivors.
Many of the dead were in the village of Pescara del Tronto which was levelled to the ground and there were fears the number of casualties could rise.
Much of the town of Amatrice was reduced to rubble and a family of four were feared dead nearby in Accumoli.
The quake hit at 03:36 (01:36 GMT), 100km (65 miles) north-east of Rome.
Although it struck at a shallow depth of 10km, its intensity was compared to the Aquila earthquake in April 2009 in which 309 people died. The epicentre was around Accumoli where several people died.
Some buildings in the capital shook for 20 seconds as the quake struck the regional border area of Umbria, Lazio and Le Marche. It was felt from Bologna in the north to Naples in the south. Some 80 aftershocks have been reported since.
Local authorities were unsure of the full extent of casualties, but 11 people were reported dead including children in the neighbouring villages of Pescara del Tronto and Arquata del Tronto. An elderly couple and a boy were among the victims.
Another 20 people have been taken to hospital. Two boys aged four and seven were pulled alive from the rubble of the house they had been staying in with their grandmother, Ansa news agency reported. Rescuers said they had been sheltering under a bed.
Rescuers were still trying to reach the remote village of Peracchia di Acqua Santa Terme a few kilometres to the east.
Some of the worst damage was in the town of Amatrice, where at least five died and rescue efforts were under way to find survivors.
“The roads in and out of town are cut off. Half the town is gone. There are people under the rubble. There’s been a landslide and a bridge might collapse,” said mayor Sergio Pirozzi.
“There are tens of victims, so many under the rubble. We’re preparing a place for the bodies,” he said.
The main street through the town has been devastated and emergency workers are trying to reach six people in a collapsed building.
The BBC’s James Reynolds, who is in Amatrice, said that sniffer dogs were being sent into buildings to search for more survivors and local authorities were trying to assess the number of people missing.
In Accumoli, a short distance to the north of Amatrice, six people were feared dead.
“There is a family of four under a collapsed house and sadly there are two small children among them,” said Mayor Stefano Petrucci.
A local photographer spoke of 15 rescuers digging with their bare hands trying reach the family.
“They can hear the screams of the mum and one of the children,” he said.
Rescuers were also trying to dig out a 58-year-old man who was trapped in his home and several more were missing. The town is popular with holidaymakers and most of the 2,500 people left displaced by the earthquake were said to be visitors.
Seismologist Andrea Tertulliani said there were sure to be further, numerous shocks that would probably diminish in intensity.
“But it can’t be ruled out that there could be another shock on the same scale as the main one,” he said.
Italy’s Civil Protection agency described the earthquake as “severe”.
“It was so strong. It seemed the bed was walking across the room by itself with us on it,” Lina Mercantini of Ceselli, Umbria, told Reuters.
Rescue teams are being sent to the worst-hit areas, the prime minister’s office said.
Why is Italy at risk of earthquakes? By Jonathan Amos
Quakes are an ever-present danger for those who live along the Apennine mountain range in Italy.
Through the centuries thousands have died as a result of tremors equal to, or not much bigger than, the event that struck in the early hours of Wednesday. The modern response, thankfully, has been more robust building and better preparation.
Mediterranean seismicity is driven by the great collision between the African and Eurasian tectonic plates; but when it comes down to the specifics of this latest quake, the details are far more complicated.
The Tyrrhenian Basin, or Sea, which lies to the west of Italy, between the mainland and Sardinia/Corsica, is slowly opening up.
Scientists say this is contributing to extension, or “pull-apart”, along the Apennines. This stress is compounded by movement in the east, in the Adriatic.
The result is a major fault system that runs the length of the mountain range with a series of smaller faults that fan off to the sides. The foundations of cities like Perugia and L’Aquila stand on top of it all.
The quake was initially reported as being magnitude 6.4. It was followed by several powerful aftershocks, La Repubblica newspaper reported.
The deputy editor of the British newspaper, The Times, who was in the area at the time, told the BBC that the quake lasted about 20 seconds followed by an aftershock about 20 minutes later which was easily as strong.
“It was pitch dark, very cold. Nobody in our group had a clue what to do in an earthquake,” Emma Tucker said.