Carbon monoxide in a south-side Thunder Bay, Ont., residence has led to the death of a 55-year-old man, police said.

Eight other people were also taken to hospital for treatment due to carbon monoxide poisoning on Sunday night, according to police.

Police, firefighters and paramedics were dispatched to the home in the 600 block of MacTavish Street, in Thunder Bay's East End neighbourhood, on Sunday night due to a 911 call.

The caller said a male without vital signs, along with three unconscious individuals, were inside the residence.

First responders detected elevated carbon monoxide levels upon arrival and entered the residence, where police officers found a conscious woman, as well as two unconscious women and one unconscious man; all were removed from the residence.

Firefighters also discovered a male without vital signs.

Four taken to hospital by ambulance

Police say four people were taken to hospital by ambulance. A 55-year-old man was pronounced dead at the hospital, and a 51-year-old man, 26-year-old woman, and 62-year old woman were all treated for carbon monoxide poisoning.

Five police officers were also treated for carbon monoxide poisoning at the hospital.

Four other individuals found in the residence did not require medical treatment. They were taken to the Balmoral Street police station to be interviewed as part of an investigation.

The residence is currently being held by police.