FIREFIGHTERS in Sicily were digging through the rubble of a collapsed apartment building today in the search for six missing people after an explosion caused by a gas leak killed at least three, the authorities said.

The building was occupied by nine members of an extended family, and two visiting relatives — a heavily pregnant woman and her husband — were also on the premises when the explosion occurred late on Saturday in the town of Ravenusa, firefighters said.

Two women were rescued overnight. One of them, 80-year-old Rosa Carmina, told La Repubblica daily that the lights went out suddenly “and the ceiling and floors collapsed.”

Her sister-in-law, who lived on the floor above her, also survived and was rescued from beneath rubble.

The explosion also knocked down three other buildings that appear to have been unoccupied, and shattered windows in three more.

“It was certainly a gas leak that created a bubble of methane,” the head of Sicily’s civil protection agency, Salvatore Cocina, told the Ansa news agency.

Preliminary investigations indicated that the functioning of a lift may have set off the explosion, which was then fed by a gas space heater.