A 74-year-old man “covered in blood” was arrested Friday night for the apparent homicide of an elderly woman found unconscious at a Bernal Heights home, police said.

Police have not released the name of the suspect, his relationship to the victim, or how she died.

Paramedics were called to a home in the 200 block of Justin Drive at 10:20 p.m. and found her lying on the floor unconscious, and the man holding a knife, according to police and fire officials.

“The suspect was covered in blood,” police spokesman Officer Albie Esparza said. He could not immediately confirm details of the incident published in a police newsletter saying the man had stabbed himself in the neck.

The man then began “advancing towards the fire crew in a threatening manner,” the newsletter said. “The crew was able to wrestle the knife from the suspect.”

Officers arrived and helped the paramedics strap the suspect to a medic backboard, according to police. The man was taken to San Francisco General Hospital for treatment of his wounds.

The victim was also taken to San Francisco General, where she was pronounced dead, Esparza said.

The Medical Examiner’s Office identified her Sunday as Hao Mei Wu, 72, of San Francisco.

aburack@sfexaminer.com