The bizarre rampage involving the dead man and a second man included the slaughter of animals and may have been fueled by a hallucinogenic drug, police said.
Police were responding to reports of the men arguing, broken car windows and trying to set their house on fire around 1:30 a.m. Officers saw broken windows on several vehicles and a naked man running into the smoke-filled home.
When they went inside the home, a naked gunman pointed a rifle at an officer's stomach, prompting the officer's partner to open fire, Lt. Lee Horton told the Vallejo Times Herald.
Investigators later inspected the rifle and found a round in the chamber, Horton said.
The man who ran into the house was taken to a hospital because he was hallucinating. Investigators were awaiting the results of toxicology tests to determine the type of drug, Lt. Sid DeJesus told the newspaper.
"We've dealt with meth, PCP before. But this is something different ... based on their rabid behavior," he said.
The house became engulfed in flames, preventing officers from searching the house for evidence. They were able to follow a blood trail that started inside the two-story house to the backyard where they found three decapitated birds, two of which appeared to be canaries, DeJesus said.
"It appeared that there was a ritualistic type of event at this place," DeJesus said. "It was an extremely bizarre situation."
The dead man's name was not immediately released, but his mother identified him to the Times Herald as Jeremiah Moore. She said her son had never been a drug addict and wasn't a violent person.
"I'm upset that this is going to be his legacy, what people are going to remember him for," she said. "He was not like this."
It was the sixth fatal officer-involved shooting in Vallejo since May.