Greek authorities say they are trying to discover what caused a two-storey apartment block in the heart of ancient Athens to collapse "in a matter of seconds", killing six people. This was reported by Qazaqyia.kz citing The Guardian.

Victims and search operation

Emergency teams found the victims, including four American tourists, on Saturday, more than 24 hours after an explosion prompted the early morning tragedy in the historic Plaka district. The fire service said the bodies of three women and three men had been found, but stopped short of identifying them. A Briton and his Greek wife, aged 77 and 78, who lived in a flat on the building's upper floor, were among those killed, the Guardian was told.

"The bodies have been taken to the morgue where postmortems will be conducted," the city's vice-mayor Paris Charlaftis said in a telephone interview from the blast scene. "Our focus now is on the explosion's cause. What could have happened to bring the building down in a matter of seconds?"

Rescue efforts

Rescuers had deployed thermal cameras and geophones, used to detect deep subsonic frequencies, in the hope of finding survivors. Earth-moving machines and specially trained search dogs were brought in to move and comb mounds of rubble through the night.

Before the bodies were pulled from the ruins on Saturday, police put the missing at six, saying four were Americans staying in a short-term rental on the building's first floor. Two brothers and their wives, all four were due to fly to the US on Friday, just hours after the explosion.

"When they failed to turn up for the flight they had checked into only a day earlier, that gave us a further lead," a source said. "It became clearer that they must have been there when the blast occurred."

The Briton, a talented artist, who lived with his wife on the second floor, was described as being partially disabled by Charlaftis. "He had kinetic issues, and it was thought likely they, too, were in the building [at the time of the blast]."

The Plaka district

Nestled around the foot of the fifth-century BC Acropolis, Plaka is especially popular with tourists. The picturesque district draws thousands of visitors daily, with many staying overnight in the hotels and short-term rentals in neoclassical houses and small apartment blocks along its alleyways and narrow streets.

The mayor of Athens, Haris Doukas, who rushed to 15 Lysikratous where the mid-20th century building had once stood, was quick to describe the incident as an "unprecedented disaster".

Casualties and witnesses

At least three people were known to have been injured when the 7.30am explosion occurred, shattering the windows of nearby buildings and scattering debris far and wide. A motorist driving down Lysikratous described how his car was lifted into the air by the sheer force of a blast that some in the neighbourhood likened to an earthquake, others to a bomb. Emergency workers could be seen hastily removing two women on stretchers from a building next door who had been wounded by flying debris.

Theories about the cause

Speculation is rife that a gas leak triggered the collapse but officials said there were many "cogent theories" at play. Fears of the leak emanating from the first-floor short-term rental was among them.

Housing crisis and criticism

As part of efforts to address a burgeoning housing crisis, Greece's centre-right government has sought to ban short-term rentals in Plaka – clamping down on permits and tightening regulations.

On Saturday, as speculation mounted over the cause of the blast, criticism grew over the ability to "properly control" establishments that were often unregulated.

"This awful incident will fuel further debate over who inspects short-term rentals that no one who lives in Plaka wants anyway," said Giorgos Zafeiriou, an architect who heads the local residents' committee. "Hotels have chambers that regulate them but who inspects and controls Airbnb and serviced apartments that often may not be up to par?"

Civil protection crews and emergency disaster management teams have been ordered to remain on site until the cause of the explosion is found, officials said.

"It was a huge explosion, so getting to the bottom of it must now be the priority," added Zafeiriou. "Six people have lost their lives."