A two-story building has collapsed in the southern Italian province of Naples, killing two young siblings and leaving their mother and another woman trapped under, Italian firefighters said.

The death toll of Sunday's collapse of a two-story apartment building in the town of Saviano, near Naples, has climbed to four after the body of an elderly woman was extracted from the rubble overnight.

Officials in Italy say a two-story building has collapsed in the southern province of Naples, killing two young siblings and their grandmother, while burying the children’s mother under the rubble.

The house is believed to have collapsed due to an explosion, local authorities said. The father of the kids and their 2-year-old brother were hospitalized after the incident.