California firefighters responding to a house fire said they found a dead man with signs of bludgeoning and his son naked and acting erratically.

The fire was reported at a two-story house on North Silverton Avenue in the city of Tujunga at about 11:53 a.m. on Monday.

The Los Angeles Fire Department said firefighters found the bludgeoned man in the backyard of the home. He was pronounced dead at the scene. Another man was found at the home, and he was treated at a hospital for symptoms of smoke inhalation and burns.

"The cause of the fire remains under active investigation," said Captain Erik Scott of the fire department. "We did bring out our arson investigators per protocol who are working very closely with LAPD to comb through the debris, look at the burn patterns, talk to witnesses, and to determine exactly what sparked this fatal fire."

The son was later taken into custody without incident after being named a person of interest in the homicide investigation. Police said they also found what appeared to be a shallow grave dug in the back yard. News video showed a bearded naked man being led away from the home in handcuffs.

Neighbors said that they believed the son had lit the home on fire and that he had been under the influence or having an episode of mental illness. They said he had been on the porch screaming incoherently before going back inside of the burning home.

LAPD Lt. Guy Golan told KTLA-TV that the man was acting erratically and "saying unintelligible things."

Neighbors said they believe that a dispute between the son and the father led to the lethal incident. Neither of the men have been identified by law enforcement. An autopsy will determine whether the father died of the beating or from the fire.

Firefighters said it took them about 23 minutes to put out the fire.

Tujunga is a neighborhood in the San Gabriel Valley of about 26,000 residents.

Here's a local news report about the incident:

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