A cargo aircraft crashed near Paleochori Kavalas in northern Greece late Saturday.
According to Greek Civil Aviation authorities, the plane operated by a Ukraine-based airline was traveling from Serbia to Jordan.
The pilot had reportedly requested clearance to make an emergency landing at nearby Kavala airport due to an engine problem but did not manage to reach it.
Communication with the plane ceased almost immediately afterward.
The aircraft was already in flames before it crashed, people close to the crash site told local media.
The mayor of the affected community of Pangeo, Filippos Anastasiadis, said that the plane had been carrying "dangerous material," likely ammunition.
He told ERT television that neither chemical nor nuclear material was on board.
Ongoing explosions at the crash site, say officials
ERT reported that it was an Antonov aircraft owned by a Ukrainian company.
The An-12, a Soviet-built turboprop aircraft, was operated by cargo carrier Meridian.
The plane crashed on farmland close to two villages that are part of the Paggaio municipality.
The fire service said in a statement that it has cordoned off the crash site.