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

Documents and belongings found on Saturday with four of the victims — two men and two women — indicated they were United States citizens, according to Greek state broadcaster ERT and other local media. Athens Mayor Haris Doukas said the blast that brought down the building in the tourist district of Plaka on Friday was believed to have been caused by a major gas leak.