A general view following an earthquake in Amatrice, central Italy, is seen in this Aug 24, 2016 handout picture provided by Italy's Fire Fighters. [Photo/Agencies]

Accumoli- A strong earthquake devastated a string of mountainous towns over a swathe of central Italy early on Wednesday, trapping residents under hills of rubble, with at least 20 people believed killed and many missing.

The quake struck in the early hours of the morning when most people were asleep, razing homes and buckling roads in a cluster of towns and villages some 170 km (105 miles) east of Rome.

The emergency services released an aerial photograph showing swathes of the town of Amatrice flattened, while debris filled the streets of nearby Accumoli.

"Now that daylight has come, we see that the situation is even more dreadful than we feared, with buildings collapsed, people trapped under the rubble and no sound of life," said Accumoli mayor Stefano Petrucci.

Wide cracks appeared like open wounds on the buildings that were still standing.

Residents were sifting through the rubble with their bare hands before emergency services arrived with earth-moving equipment and sniffer dogs.