Police said the upstairs neighbour called 911 and reported hearing multiple loud shots at approximately 6:17 a.m. PT.
Police blocked off the road outside the home where the body was found, in the 500 block of Colby Street, near Holmes Street.
Police said the identity of the man not yet known.
Investigators worked throughout the morning to assess the cause of death.
Before noon, police determined that the death was suspicious, and turned the investigation over to the region's Integrated Homicide Investigation Team (IHIT).