ATHENS, Greece (CNN) -- A Cypriot plane carrying 121 people crashed north of Athens on Sunday, Greek officials said.
Helios Airlines Flight 522 with 115 passengers and six crew crashed en route from Larnaca, Cyprus to Athens, officials said.
Lefterios Ikonomou, a senior public order ministry official, told CNN the site of the crash was in Varnava, near the historic town of Marathon, about 50 km (31 miles) north of Athens.
Authorities sent two Greek F-16 jets to escort the plane after the control tower at Athens international airport lost contact with the pilots, state media reported.
One of the F-16 pilots reported he could not see the captain in the cockpit and that the co-pilot appeared to be slumped in his seat, a Greek Defense Ministry official told Reuters.
The official said police and military helicopters were at the scene, and dozens of ambulances were on their way, Reuters reported.
Military helicopters spotted some debris and smoke but no movement on the ground, Reuters said.
Reuters describe the scene as an uninhabited mountainous bushland area which is difficult to reach.
But Miltiadis Merkouris, a spokesman for the coastal municipality of Grammatikos near the crash site, told The Associated Press the site was about 400 meters (yards) from homes in the area.
Witness Dimitris Karezas, who owns a summer camp in the area, said, "I saw the plane coming. I knew it was serious or that it was some kind of VIP because I saw the two fighter jets.
"Two, three minutes later I heard a big bang and ever since I've started looking for it, but I have not found anything yet," he told reporters.
Helios Airlines is a subsidiary of Cyprus Airlines.
