Officers responded to a report of an unresponsive person on the ground in the area of North Second and East Saint John streets at about 2:50 a.m., Sgt. Heather Randol said.
When officers arrived, they found a male on the ground. He was pronounced dead at the scene, Randol said.
The victim's name has not yet been released.
No suspects have been identified or apprehended and investigators continue to look into what led to the homicide, according to Randol.
The murder is the city's 10th of the year.
Santa Clara Valley Transportation Authority bus and light rail service has been disrupted due to the investigation. Light rail will not stop at Saint James station and buses are being rerouted during the investigation, according to VTA officials.