Authorities on Thursday were investigating the shooting deaths of two men whose bodies were discovered in two neighboring backyards.
The men, who have not been identified, were found dead about 7:30 p.m. Wednesday in the neighboring backyards in the 100 block of Carlotta Circle in the unincorporated community of Mill Valley, Marin County sheriff's Lt. Doug Pittman said.
Although the deaths are suspicious, Pittman said detectives believe it was an isolated incident.
Detectives are still trying to piece together the events that led up to the deaths. It is also unclear how the men knew each other, Pittman added.
The first death was discovered after the man's family found him lying in the backyard and thought he had suffered a medical emergency.
Deputies arrived at the home and couldn't immediately find any obvious signs of trauma.
"It didn't feel like a crime scene," Pittman said.
Soon after, a coroner's investigator, who is also a pathologist, discovered an entry wound from a gunshot.
As detectives secured the crime scene and talked to witnesses, they spotted a gate leading from the frontyard to the backyard of a neighbor's home.
They moved in to ensure the area was safe and discovered the second man, who had appeared to have a suffered a gunshot wound.
Detectives found a rifle near the body, Pittman said.
Witnesses later told detectives they heard gunshots sometime Wednesday afternoon.