Firefighters responded to a small fire at 4:39 a.m. near Buena Vista Avenue East and Haight Street, a fire dispatcher said.
While extinguishing the blaze, a small brush fire near trash cans, firefighters found the partially burned body of a victim who was already dead, police Lt. Troy Dangerfield said.
Police are considering the death suspicious. Homicide inspectors and the arson task force are investigating the incident, Dangerfield said.
No information about the victim was immediately available this morning, he said.
Anyone with information about the case is encouraged to call the Police Department's anonymous tip line at (415) 575-4444 or send a tip by text message to TIP411.