Oakland police are investigating whether the incident was a homicide, and the coroner's office has been called to the scene, according to Lt. Henderson Jordan.
Fire crews were dispatched to reports of a fire in the 1800 block of 34th Avenue around 5 a.m., according to Oakland fire Battalion Chief James Bowron.
Crews arriving on the scene realized the blaze was mainly burning the outside of an apartment building. Firefighters then discovered a badly burned body in an alleyway in between two apartment buildings, Bowron said.
Crews quickly extinguished the blaze and kept it from spreading to a neighboring building, he said.
An arson investigator and Oakland police were called to the scene.
Fire and police are working together to determine what caused the fatal blaze, but Bowron said the fire is considered suspicious.
It is unknown whether the victim was a male or female, police and fire officials said.