All 121 people aboard a Cypriot airliner died on Sunday after it smashed into a wooded hillside near Athens after air force pilots said the crew of the Boeing 737 appeared 'doubled up' in the cabin.
In Larnaca, Cyprus, operator Helios Airways and a Greek government official in Athens said there were no survivors among the 115 passengers and six crew.
A Cypriot official said first indications from the Greek authorities were that the crash was not caused by a terrorist attack.
Police said the disaster could have been caused by a sudden failure in the pressurisation or air-conditioning system.
Firefighters searched for bodies among the smoking wreckage, which was scattered over a wide area, after water-dropping aircraft and helicopters were called in to extinguish a fierce blaze.
The Helios Airways twin-engine jet was about to land at Athens airport for a stopover on its journey from Lanarca in Cyprus to the Czech capital, Prague.
Czech Prime Minister Jiri Paroubek said 80 of the passengers were Greek school children returning from a holiday in Cyprus. But a fire department spokesman said, "According to our information, there were a dozen children aboard."
It was Greece's worst air disaster since 1974, when a terrorist bomb aboard a TWA Boeing 707 caused it to crash in the Ionian sea with the loss of 88 lives.
Greek and Cypriot officials said communications with the Cypriot aircraft were suddenly lost.
Two air force F16 fighters scrambled to investigate and found the Cypriot plane drifting above the Euboea peninsula northeast of Athens.
Iannis Pantazatos, who was in charge of the control tower at Athens International Airport, said the air force flyers 'saw the pilots doubled up in the cabin'.
Minutes later the plane crashed at Varnava, a largely uninhabited area 40 km northeast of Athens.
"An act of piracy is likely," said a spokesman for the Greek army, Gerassimos Kalpoyannakis. He said pilots of the two F16 fighters that were sent up to escort the airliner before the crash 'saw a situation that was not normal in the
In Nicosia, Communications Minister Haris Thrassou said, "Contact with the pilots and the control tower" was suddenly cut as the airliner approached Athens.
"Two figher jets from the Greek air force escorted the plane, but unfortunately a few minutes later it crashed," he added.
Government spokesman Theodoros Roussopolos cautioned that the cause of the crash was unlikely to be known until investigators examined the plane's flight recorder and cockpit voice recorder.
"We're plumping for an accident, but cannot rule out other possibilities as long as the black boxes have not been analysed," he said.
Helios Airways said it was 'unclear' what caused the crash.
A senior official at the public order ministry, however, speculated that a sudden drop in cabin pressure could have caused the disaster.