At about 1:18 a.m., police received a report of an injured man lying in a parking lot in the 400 block of Blossom Hill Road in South San Jose.
Officers arrived at the scene and located an unconscious man. The man appeared to have been assaulted, police said.
San Jose fire responded to the scene and declared the man deceased.
The San Jose Police Department's Homicide Unit responded to take over the investigation.
No suspects have been identified, police said.
The identity of the victim is being withheld pending notifications to his next of kin.