Officers responded to a call about the shooting around 3:39 p.m. in the 400 block of Drave Avenue near Cole Drive, where there is still an active crime scene.
When they arrived, authorities found an unresponsive male, age unknown, unresponsive. He was pronounced dead at the scene, the sheriff's office said.
Officials say there is no threat to the public, but they are asking that people avoid the area.
There is a large police presence at the scene. The case is being investigated as a homicide.
Further details were not immediately made available.
VIDEO: Large police presence at scene of deadly Marin City shooting
Large police presence at scene of deadly Marin City shooting
Stay with ABC7 News for the latest details on this developing story.