The 44-year-old man was attacked as he was taking out his car to take his pregnant wife to hospital to give birth to their second child.
Police said the man was heading for a parking lot near his home in the Patissia district when he was attacked by three assailants and suffered at least three stab wounds in the back, hands and neck as he tried to escape.
The attackers grabbed his camera and fled.
The victim's wife and mother-in-law, who were waiting in the couple's apartment for the man's return, seeing he was delaying, decided to go down to the sidewalk to wait for him, where they found his body.
The two women suffered a strong shock, and neighbors called for an ambulance to take him to hospital, where he was pronounced dead on arrival.
According to information gathered by police, the perpetrators were three dark-skinned men, possibly foreign nationals.
Security police were searching for the perpetrators.
Protest rally at location where 44-year-old was killed in downtown Athens
About 200 people held a protest rally, at 5 in the afternoon, at the location where a 44-year-old was killed on Tuesday morning while preparing to take his car to transfer his wife to a maternity clinic to give birth.
Due to the rally, 3rd September street was closed from Marni street onwards and Ipirou street from Aristotelous street.
According to information reaching the police, there was tension in the region and attacks against foreigners have taken place. Police forces are on standby in the event incidents take place.