There was a shout for help, a call to police and then a knock on the door.
About 5:30 a.m. Friday in San Leandro, officers didn't know what they would find when they investigated reports of a disturbance in an apartment in the 900 block of Juana Avenue.
But as soon as a man opened the door, they knew it would be bad: He was covered in blood.
Somewhere behind him inside another room, police said, lay the body of his father.
"We offer our condolences to the family and friends of the victim in this morning's tragic incident," police Lt. Robert McManus said in a statement.
The 21-year-old man who was covered in blood was arrested on suspicion of murder, police said in a statement. Police declined to provide the name of either the victim or the son.
Police said several neighbors had called 911 after hearing what sounded like a confrontation and a man inside shout for help.
It was not clear if the man and his father lived together, but the son was there frequently enough that neighbors would have assumed he did, McManus said.
The man allegedly stabbed his father to death, but police don't know why. A day earlier, an off-duty Richmond police officer was shot to death by his grandson's father in Vallejo.
Investigators were at the home Friday afternoon interviewing witnesses and combing the scene for evidence, officials said.
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