Two women reportedly injured in blast in Athens’ historic Plaka district, buildings evacuated.

Rescue teams have recovered the bodies of six people killed in a building collapse following a a blast in the historic centre of Athens, Greece, according to local authorities.

Documents and belongings found with four of the victims – two men and two women – on Saturday indicated they were United States citizens, Greek state broadcaster ERT and other local media reported.

The other two victims were reportedly an elderly couple, a British man and a Greek woman, who lived on the building’s second floor.

Two women were injured in an adjacent building, according to the fire department.

The blast that brought down the small, two-storey building in the popular tourist district of Plaka on Friday was believed to have been caused by a major gas leak, Athens Mayor Haris Doukas said. Neighbouring buildings were damaged and evacuated, he said.

“The damage extends to the entire street as well as the street behind [the building],” Doukas said. “We are talking about an unimaginable catastrophe.”

Two adjoining buildings severely damaged might have to be demolished, he said.

The Greek daily newspaper Kathimerini reported on Friday that the four tourists, who were due to leave their accommodation at about 11:00am (08:00 GMT), failed to board their flight back to the US.

Plaka residents issued warning

A group of Plaka residents had alerted the municipality and the managers of the electricity and gas networks about the risks of short circuits or gas leaks in the area a year ago.

In a letter published by Kathimerini, the group called for the organisation of a security exercise to identify any potential shortcomings in the emergency response system.

The citizen movement “We Remain Active” also stated on social media that a resident of the street where the explosion occurred had reported a smell of gas for several weeks and had warned the authorities.

A Greek police spokeswoman confirmed on ERT that residents had made the report. However, the nature of the substance and its origin have not yet been determined.

Plaka lies at the foot of the Acropolis, Greece’s most visited ancient monument.