The bodies of three women and two men have been found in a home across the street from a private high school in a quiet neighborhood and police are investigating the deaths as a possible murder-suicide.
A woman with access to the house discovered three of the bodies around 8 a.m. Friday, police said.
She found one man shot to death in the foyer by the front door, said Police Chief Greg Suhr. She then saw a man and a woman dead in the garage before running out and calling police.
When officers arrived, they found the other two deceased women. Police spokeswoman Cmdr. Lyn Tomioka said at least two of the victims were shot, and investigators were still looking into how the others died.
"It's kind of frightening. It's usually quiet over here," said Mark Wong, 45, who lives on the next block. "Nothing like this has ever happened before."
The identities haven't been released but police said that at least four of the people were related.
Tomioka stopped short of confirming it was a murder-suicide but said no suspects were being sought outside the home.
"We do not believe we have a suspect at large," she said. "We do believe at this stage that this incident is specific to this address."
Police said Friday evening there was no new information to release in the investigation.
The neighborhood in the southern part of the city is home to Lick-Wilmerding High School and San Francisco's City College, in addition to a thriving immigrant community, largely from Asia.
Mayor Ed Lee called the incident a terrible tragedy.
"As the San Francisco Police Department thoroughly investigates this incident, I extend, on behalf of the city, our support and sympathy to all family members and friends of the victims involved in this crime," Lee said in a statement.
Investigators believe all of the victims lived in the orange, two-story home in the Ingleside District.
Rick Moody, 50, who lives across the street, said his wife heard some shouting late at night.
"We're surprised that it happened in our neighborhood," he said. "This area is very safe."