The man in his 60s lived in an apartment detached from a house in the 2400 block of San Medina Avenue.
When firefighters arrived around 3 a.m. Monday they found the apartment engulfed in flames.
"Once he kicked in the door he started yelling for him, but he couldn't get in because of the fire and he got no response from my uncle. By the time the fire department got here it was too late," said Willie Williams, the victim's nephew.
Five family members live in the main house. It was also damaged, but no one inside was hurt.
The apartment had central heat and air, but family members said the man also had an electric space heater. They suspect it may have sparked the fire.
The official cause is still under investigation.