Two students have died in Larissa, central Greece, from carbon monoxide poisoning and another three are in a serious condition in a local hospital.
Authorities said the five students had fired up a charcoal grill in their apartment on Thursday afternoon to cook some meat and then left the fire burning in order to heat the property.
Coroner Christos Kravaritis told Skai TV on Friday that initial tests showed the students had consumed alcohol.
The five men were discovered by a friend who visited the apartment and was able to open the door with the help of a landlady.
The two students were pronounced dead at the apartment and the other three were hospitalized.
Two of the three are in comas.