Thirteen men from the fire brigade's special teams as well as 26 firemen are near the crash site.
Video footage from a local channel showed signs of impact on a field and the aircraft in pieces scattered at a long distance.
The Antonov An-12 cargo aircraft crashed late Saturday near Paleochori village in northern Greece, the fire brigade said.
Videos shared by eyewitnesses on social media showed the plane engulfed by a giant fireball as it hit the ground.
Eyewitnesses said the aircraft was on fire and that they had heard explosions.
People living within a two-kilometre (1.2-mile) radius around the crash site were asked to stay inside their homes and wear masks on Saturday night.
Two firemen were taken to the hospital early Sunday with breathing issues because of the toxic fumes.
A local man, Giorgos Archontopoulos, told state broadcaster ERT television he had felt something was wrong as soon as he heard the aircraft's engine.
"At 2245 (1945 GMT) I was surprised by the sound of the engine of the aircraft," he said. "I went outside and saw the engine on fire."
Local officials said seven fire engines had been deployed to the crash site but that they could not approach because of the continuing explosions.
According to media reports, the cargo aircraft was flying from Nis airport in Serbia to Jordan's Amman and had requested clearance to make an emergency landing at nearby Kavala airport, but did not manage to reach it.
ERT reported that it was a Ukrainian aircraft, which according to villagers was already in flames before it crashed.
There is no official information about the number of people onboard the plane.
But ERT reported it was carrying eight people and that its 12-tonne cargo "was dangerous".
Police were last night asking journalists at the scene to wear masks, the report added.
"You need to go away for your safety. There is information that the aircraft was carrying ammunition," one fire-fighter told reporters at the scene.
"The aircraft crashed around two kilometres away from an inhabited area," Filippos Anastasiadis, mayor of the nearby town of Paggaio, told Open TV.