It happened on Moraga Street between 30th and 31st Avenue. Police arrived at around 5:45 p.m. after they got a call that something suspicious was going on inside that home.
When police arrived, they found a 40-year-old Asian male -- who is likely the home owner -- shot to death and several adult women tied up inside the house.
"We can't rule anything out. We don't know what happened, we're trying to find out," said San Francisco Insp. Kevin Jones.
A woman who lives nearby heard the gun shot. She spoke to ABC7 through a translator and did not want to be identified.
The woman said the gunshot sounded "like a big bomb, a big sound." She looked out of the window, saw there was a police car, then went down stairs and saw the mother. That woman told her that someone shot her son and that he was dead.
Police say two masked and armed men broke in, tied everyone up then ransacked the place.
It is not clear what was taken or what they were looking for, but the home owner had surveillance cameras installed.
A neighbor said the gunshot victim and his mother moved in three years ago and that she noticed young women regularly coming and going from the house.
ABC7 was told all of the people who were tied up are co-operating with police. The gang task force has also been brought in to help.