Reports said the pilots were unconscious when the plane went down, possibly because of a lack of oxygen in the cabin. A Cyprus government spokesman said there are no indications that terrorism caused the crash. The plane's black boxes, which contain flight data and voice recordings, had been recovered at the scene, state NET television reported.
The Helios Airways flight HCY 522 was headed from Larnaca, Cyprus to Athens International Airport when it crashed at 12:20 p.m. near the town of Grammatiko, about 25 miles north of the Greek capital, leaving flaming debris and luggage strewn across a ravine and surrounding hills. It was carrying 115 passengers and six crewmembers.
The Boeing 737 was due to fly onto Prague, Czech Republic after stopping in Athens.
"The fire is still burning and there are no survivors," fire chief Christos Smetis said.
Among the passengers were 48 children. CBS News Correspondent Larry Miller reports the children were Greeks returning from a vacation to Cyprus.
Sotiris Voutas, the cousin of a passenger, told Greece's Alpha television that he received a text message on his mobile phone minutes before the crash.
"He told me the pilots were unconscious ... he said: "Farewell, cousin, here we're frozen."
The coldness in the cabin suggested "the crew may have been suffering from lack of oxygen," said David Kaminski Morrow, deputy news editor of the British-based Air Transport Intelligence magazine. Oxygen masks should have automatically deployed and there should have been enough oxygen to allow the crew to bring the plane down to an altitude of about 10,000 feet where the air is breathable, he said.
"The key questions are at what altitude was all this taking place," Kaminski Morrow said.
Alpha TV said Greek air force officials reported that the pilots of two F-16 jet fighters that intercepted the plane over the Aegean Sea shortly before it crashed saw one of the pilots slumped unconscious over the controls. They also reported that there was no movement in the cabin.
Greek state television quoted Cyprus Transport Minister Haris Thrasou as saying the plane had decompression problems in the past.
Sudden loss of cabin pressure was blamed on a similar crash that took place in the United States on Oct. 25, 1999. At the time, a private Learjet 35 lost pressure and left pro golfer Payne Stewart and four others unconscious. The twin-engine jet went down in a pasture in South Dakota after flying halfway across the country on autopilot.
In the Greek crash, the only piece of the plane that remained intact was the tail section of the jet. Bits of human flesh, clothing, and luggage were scattered around the wreckage, which also started brush fires around the area.
Rescue helicopters flew overhead and firefighting planes swooped low to extinguish some of the fires. Fire trucks and ambulances crowded the roads near the crash site and dark black smoke could be seen rising from various sites around the crash. A number of black-robed Greek Orthodox Christian were also on the scene.
"There is wreckage everywhere. I am here, things here are very difficult, they are indescribable," Grammatiko Mayor George Papageorgiou said. "I am looking at back tail. The fuselage has been destroyed. It fell into a chasm and there are pieces. All the residents are here trying to help."
The head of the Greek airline safety committee, Akrivos Tsolakis, described it as the "worst accident we've ever had."
The two F-16 fighter jets were scrambled shortly after the plane entered Greek air space over the Aegean Sea and did not respond to radio calls. It is standard Greek air force procedure to intercept any aircraft entering the country's airspace that do not respond to radio calls.
Witnesses said they saw the plane being followed by the Greek air force jets when it crashed.
Greek radio and television stations reported that the air force pilots saw no movement in the cockpit of the plane before the crash. There were some reports the two pilots seemed to be unconscious.
"The plane crashed around 400 meters (yards) from homes in the area," said Miltiadis Merkouris, a spokesman for the Grammatiko municipality.
Helios Airways was founded in 1999 as Cyprus' first independent airline.
It operates a fleet of Boeing 737 jets to cities including London; Athens; Sofia, Bulgaria; Dublin, Ireland; and Strasbourg, France.
Greek Prime Minister Costas Caramanlis canceled a holiday on the Aegean island of Tinos to return to Athens to deal with the crash. Cypriot President Tassos Papadopoulos also canceled a vacation.