The magnitude 6 quake struck at 3.36am local time and was felt across a broad swathe of central Italy, including the capital, Rome, where residents felt a long swaying followed by aftershocks.

The hardest-hit towns were Amatrice and Accumoli near Rieti, some 100km north-east of Rome, though the quake was felt beyond the Lazio region into Umbria and Le Marche on the Adriatic coast. At the moment, it is known about the death of 21 people and dozens of wounded. About 100 citizens are considered missing.

The centre of Amatrice was devastated, with entire palazzos razed to the ground. Rocks and metal tumbled on to the streets and dazed residents huddled in piazzas as dozens of aftershocks continued into the early morning hours, some as strong as 5.1.

Photo: The city of Amatrice after the earthquake.

Facebook has activated its "Safety Check" feature in Italy following an earthquake in the country that has levelled buildings and killed at least 21 people.

The feature allows people in the area to mark themselves as "safe" on the social network — and will show users a list of their friends in the area that have also been marked safe. It will also send a notification to users when friends mark themselves safe.

Amatrice became a victim of a landslide, which came down immediately after the tremors. The Mayor of Amatrice said half of the town 'was not here any more' after the severe earthquake hit the central Italy.

Rescue teams using bulldozers, and aided by townspeople with their bare hands, were still poring through the piles of rock, metal and wood late Wednesday looking for possible survivors. The population of the city is three thousand people.

Seismologists do not exclude the possibility of the repetition of powerful tremors.

Photo: Rescuers work at a collapsed house following a quake in Amatrice, central Italy, August 24, 2016.

The representatives of the National Civil Defense Service assured all residents of the affected areas of providing specialized assistance, noting that some settlements are difficult to reach at the moment.

Photo: The residents of the city of Amatriache.

The worst hit towns were believed to be Accumoli, Amatrice, Posta and Arquata del Tronto, spokesman for the Italian fire department Luca Cari told Reuters.

Photo: The residents of Amatriace try to get people out of the rubble on their own.