Police did a house-by-house, yard-by-yard search for the suspect who is described as a Filipino man. Officials say a brief conversation took place between the two before the man stabbed the woman multiple times. It's not clear whether the victim and the suspect knew each other.
There were many witnesses in the vicinity. The county office building and the sheriff's department are right across the street. And right next to the parking lot is a sandwich shop where an employee, Ana Jimenez, told us she saw the woman lying on the ground.
"A lot of people come into the Togo's and say, 'Oh, close the door, close the door, somebody killed somebody on the side,'" Jimenez said. "I see from the window and the lady's on the floor, but I only saw the shirt for the guy."
Matt London was eating lunch at the nearby Togos when he heard a commotion and rushed out to help the woman who was slashed on her neck and arms.
"I held her head up, kept pressure on it, and I said, 'Who did this? Can you give me a name, any name?' and she couldn't really talk," said London.
He too was covered in blood when paramedics arrived.
"I feel like it was horrible for her to have to die that way and I just hope that by my being there, maybe it wasn't as bad a way to die," said London.
London walked to North Second Street where he was doing handiwork and had to convince police he was not the killer. Police say the real culprit hopped a fence and ran through this neighborhood where detectives found blood in front of some homes.
"The detectives just came by and circled where the blood things are," said Michelle Rojas, a San Jose resident. "We've been told to stay in our house with our doors and windows locked. We're not even allowed to come out to our front yard."
Burnett Middle School is just around the corner. While police say the school was not officially locked down, students were kept inside until they could be released to their parents. They were advised to leave the school to the south, opposite from where the search for the suspect is underway.
San Jose police believe the suspect didn't get far and may be hiding in a residential backyard somewhere between First and Fourth streets, north of Hedding.
They brought in police dogs, special operations officers, and even the CHP helicopter was pressed into service to check out rooftops and keep an eye on the periphery just in case the suspect made a break for it.
The man is armed with a knife, and police are also concerned that he may have other weapons in his possession. So the search is a delicate one in which officers could be facing a high-risk confrontation with the suspect.
Police are trying to figure out what led up to the attack.
"Basically the male subject approached the female victim. There was some type of contact. We don't know if there was a conversation there, if they knew each other, or what the connection was, but during that contact, our male suspect stabbed our female victim multiple times," said San Jose Sgt. Jason Dwyer.
Police have not released the victim's name. Rojas told us that she heard police say that they do know who they are looking for in this case.
This was San Jose's 10th homicide of the year.
ABC7 News reporter John Alston contributed to this report.
