Italian media quoted the civil protection agency as it provided the latest toll. The quake was felt as far away as Rome, which lies about 150 kilometres south-west of the epicentre.
According to an earlier count by the ANSA news agency, six of the dead were from the town of Accumoli, five from Amatrice, and 10 from the town of Pescara del Tronto.
The toll is expected to rise further as many victims are trapped under rubble.
‘This is a town that is dead. It's completely destroyed,’ Federico Rocchi, a student in his 20s told dpa in Amatrice, adding that he also lost many friends.
The Italian Institute of Geophysics and Vulcanology (INGV) said the magnitude-6 quake that struck at 0136 GMT had its epicentre at a depth of 4.2 kilometres in a wooded area in the province of Rieti.
It was followed by more than 50 aftershocks, the strongest a 5.4-magnitude quake at 0233 GMT.
‘Many are still trapped under the rubble,’ Amatrice Mayor Sergio Pirozzi told ANSA. ‘We're preparing a spot for the bodies.’ ‘Half of the town is gone,’ Perozzi told public broadcaster Rainews 24.
Resident Eraldo Di Giacomo spoke of major devastation: ‘Everything has collapsed, houses, everything,’ he said in an interview with the same network. ‘Everything is broken.’ Amatrice's hospital was evacuated, and its 15 patients were moved out into the street. People injured from the earthquake were also taken there.
But there were also signs of hope.
One boy was pulled alive from the rubble in the town of Pescara del Tronto. Doctors also freed a 6-year-old boy from the rubble in Amatrice, though his twin brother remained missing, reported ANSA.
Speaking to Rainews 24 two hours after the quake hit, Accumoli Mayor Stefano Petrucci complained that emergency services had not yet arrived, putting lives at risk because locals were ill equipped to search for survivors.
‘It is a scandal,’ Petrucci said, noting that a Carabinieri police unit had managed to reach the town from 100 kilometres away.
‘We have news of injuries and collapses,’ the head of the Civil Protection agency, Fabrizio Curcio, earlier told Rainews24. ‘Right now the priority is saving human lives,’ he added in a press conference.
Italian President Sergio Mattarella appealed for solidarity during a ‘moment of pain and of appeal to common responsibility.’ ‘The immediate need is to engage all forces to save lives, care for the wounded and ensure the best conditions for the displaced,’ he said.
The disaster has already prompted an outpouring of sympathy.
Pope Francis said he was nearly at a loss for words.
‘Hearing the mayor of Amatrice saying that the town doesn't exist any more and knowing that there are children among the victims has moved me deeply,’ he said.
German Foreign Minister Frank-Walter Steinmeier said his country will provide support to its ‘Italians friends and partners’ if needed. ‘In this hour we stand united in mourning and solidarity with our Italian friends and partners.’ Condolences also came in from Russian President Vladimir Putin and European Parliament President Martin Schulz.
‘Russia shares the sorrow of the Italian people,’ Putin said in a message to Italian Prime Minister Matteo Renzi, according to a statement on the Kremlin's website.
He said Russia is ready to ‘provide the necessary assistance for eliminating the consequences of this natural disaster.’ The Umbrian town of Norcia, which was hit by a major earthquake in 1979 killing five people, was earlier indicated as the epicentre by the US Geological Survey. Nobody was hurt there, the local municipality said.
Norcia is also 55 kilometres north of l'Aquila, where a 5.9-magnitude quake killed 309 people seven years ago.
Curcio said the latest seismic event was ‘severe’ and ‘comparable’ to the L'Aquila earthquake in its intensity, but was likely to be less deadly because it took place in an area that is less densely populated.
‘What we say in L'Aquila years ago has now happened here,’ said Petrucci, speaking to Rainews24. ‘We need help.’