ST. PAUL -- Authorities are working to determine what killed a man found dead in a St. Paul house fire.

Neighbors reported smoke coming from the Eastview neighborhood house around 6 a.m. Saturday. Firefighters extinguished a fire in the basement and found a 64-year-old man dead in a living room chair. They found no other victims.

Neighbors said the man lived alone and was using medical oxygen. He appeared to have health issues that might have impaired his ability to move.

The Ramsey County medical examiner is working to determine the man's identity and the cause of death. The St. Paul Fire Department as well as the state fire marshal's office are investigating the cause of the fire.