Police broke down the door to a family residence in Benin City to find seven people unconscious.
One person has died and six others are in hospital.
They were said to have eaten a meal and gone to sleep but did not wake up next morning.
A police source anonymously told Daily Trust that fumes from a generator which the family turned on at night may have been responsible.
The incident happened at No 40, Otete Street, off Textile Mill Road, Ogida quarters, Benin City.
The place was deserted when correspondents visited, while a few sympathisers were seen outside the compound.
Neighbours suspect food poisoning.
“The man lost his wife last week Sunday and today making it five days now,” a neighbour, Rachel Anyanwu, said of the father of the family.
“Those who were rushed to the hospital this morning were his children and other relatives who came to sympathize with the man over the death of his wife.”
A resident, Christy Igbinadolor, living opposite the victims’ home said they got to know of the incident when a man came to inquire the where about of the family from her.
According to her, the man told her that it was their elder brother in PortHarcourt who called him to come down and find out what was going on as they were not answering his calls.
She said she advised him to knock at their door and if there is no response, he should go to the police station and report.
She said it was when the police broke the door that they found them lifeless and rush them to the hospital.
Police is yet to comment on the incident.
