At least three people have been killed after an explosion caused multiple residential buildings to collapse on the Italian island of Sicily.

Authorities on Sunday said two women were recovered alive from the rubble in the southern town of Ravanusa after the collapse on Saturday night.

Rescuers, sniffer dogs and a drone have been deployed to locate the missing, Sicily’s regional civil protection unit said.

The local authority confirmed on its Facebook page that three people were killed in the blast, which affected at least four buildings. It did not specify how many people are estimated to be missing.

Authorities said the explosion appeared to have been caused by gas.

Television images showed a mass of rubble, wooden beams and mangled steel in a large empty space in Ravanusa’s centre, with neighbouring buildings charred and damaged.

Italian Firefighters are searching for survivors following a gas explosion in Ravanusa, Sicily [Vigili del Fuoco/AFP]

A “huge shock wave” from the explosion was felt 100 metres (330 feet) away, said Salvatore Cocina, head of Sicily’s civil protection unit.

Authorities have opened an investigation to determine what caused the blast.

“The gas probably found a cavity in which to accumulate,” the head of firefighters in the province of Agrigento, Giuseppe Merendino, told the Rainews24 TV channel.

“This pocket of gas would then have found an accidental trigger: a car, an elevator, an electrical appliance.”

Soon after the explosion, Ravanusa Mayor Carmelo D’Angelo appealed on Facebook for “everyone available who has shovels and bulldozers”.

“There has been a disaster,” he said.

About 50 people have been displaced due to the incident, D’Angelo told Rainews24.