Vasilis Vathrakogiannis, a spokesperson for the Hellenic Fire Service, told the BBC the alarm was raised by a friend of the three men after they failed to return at the expected time.
“Weather conditions were extremely difficult, with low temperatures and poor visibility,” he said, adding this made it hard for both drones and a helicopter to detect anything.
He said a fire service ground team later found the bodies of the three men and a woman, who was confirmed to be a friend of one of them and had not been expected to take part in the climb.
Recovery efforts were under way on Saturday, in what officials described as an extremely challenging operation.
One of the bodies was successfully airlifted by helicopter. Efforts continue to move the remaining three to a nearby plateau so they can be recovered using a winch.
Haris Asariotakis, head of the Hellenic Rescue Team mission at the scene, said the location was particularly difficult.
“It is about three hours from the village of Athanasios Diakos, at an altitude of 2,000m,” he said. “If the helicopter is unable to reach the area, we will descend on foot together with firefighters and mountain guides.”
Additional reporting by Kostas Koukoumakas