Officers remained on scene all day, gathering evidence. ABC7 News has learned the names of the two, but we are withholding them because the coroner has not released them and we do not know if next of kin has been notified.
We also learned that the woman apparently filed a restraining order against the man last fall, charging domestic violence.
Sunnyvale police arrived at the home shortly after 8 a.m. after receiving a disturbing call.
"We received a phone from a male subject saying he had killed someone inside a residence," Captain Dave Pitts said.
Police, including members of the SWAT team, surrounded the house. They tried to make contact with the man inside.
"After numerous attempts via phone calls and bullhorns, there was no response at the residence," Pitts said.
Shortly after 10 a.m., SWAT team members began approaching the door of the house.
Neighbor Tom Cottam says he was outside his home at the time, "Then all of a sudden later on, I heard the pop pop pop sound, and then I think they got the guy."
In video we shot just at that moment, you can hear an officer telling the man to come out with his hands up.
As police methodically searched the home, they came upon a female body. Police withheld the name of the resident and that of the dead woman.
But we have learned that he owns a metal works company just a short drive from his home.
Police had cordoned off the triplex, which tenants told us he owned.
He used one unit as his office and rented out the others. People we spoke to here who knew him said he was a nice quiet guy, but kept to himself.
Carl Huerta manages the apartments next door.
"It was just a casual friendship," he said. "I didn't even know his last name until you told me."
Neighbors say this is a peaceful neighborhood. They can't remember the last time police were called here.