This is the dramatic moment a four-year-old girl was pulled from the rubble alive after her sister, eight, sacrificed her own life by throwing herself on top of her as wreckage from Italy's devastating earthquake encased them.

In one of the most remarkable stories of courage to emerge from the catastrophic 6.2-magnitude quake that struck central Italy on Wednesday, the two girls were found buried together in the rubble of their holiday home in the village of Pescara del Tronto but only one of them survived.

Distraught grandmother Angela Cafini wept as she recalled how her four-year-old grand daughter escaped with barely a scratch thanks to her older sister who lay on top of her to protect her as the house collapsed around them.

'Giulia died saving her sister. She lay on top of her. That is the only reason she is alive. I am told she has no injuries and that is the only explanation for that,' Ms Cafini said.

The village has been virtually wiped from the map with almost every building destroyed.

The astonishing tale of heroism emerged as the death toll from the earthquake rose to 250.

Officials fear the final number of victims will be more than 500 as they continue their painstaking search through the shattered remains of four villages looking for more survivors.