Eighty-five people were also injured, said Vassilis Vathrakogiannis, the representative of the Fire Service, at the fourth briefing, as reported by Greece's public broadcaster ERT.
Of the injured, 25 are in critical condition, said Vathrakogiannis.
The passenger train was reportedly carrying 250 people and was on its way from Athens to Thessaloniki.
According to reports, several carriages came off the rails and at least three of them caught fire.
At least 30 ambulances were dispatched to the scene.
Search and rescue efforts remain underway at the crash site.
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