The man's identity has not been released.
Deputy police chief John Ercul says the Pueblo fire department and Colorado Bureau of Investigation are helping to investigate the cause of the fire. Ercul says it appears the fire was accidental.
An autopsy on the victim, a male in his 60s, is underway to determine cause of death.
The victim's roommate survived the fire. He dragged the unconscious victim outside, where paramedics worked on him before transporting him to St. Mary Corwin hospital. The man was pronounced dead at the hospital.
The fire was quickly extinguished but was a total loss, along with two vehicles. Mobile homes on either side were also damaged.