The incident happened around 3 a.m. Tuesday on the 2900 block of Frankford Avenue.
PHOTOS: Slashing in Port Richmond
Paul Raab couldn't believe what he saw as the woman clutched her throat and stumbled towards him.
"She had her hand around her neck and she couldn't speak."
Raab was walking his dogs near his home, and at the same time a friend happened to be driving by with his wife. They stopped, called 911 and then tried to help.
"His wife got a towel out of the back of the car and put it around her neck. And the cops came ... not even a minute later. He threw her in the back of the cop car," Raab said.
Police say officers drove the victim, described as a woman in her 40s, to Temple University Hospital where she was rushed into surgery in critical condition.
Police say she lost a lot of blood, and her throat was slashed twelve inches across.
Investigators are still trying to determine the victim's identity and where she came from.
RAW VIDEO: Woman's throat slashed in Port Richmond
Philadelphia Police Chief Inspector Scott Small says, "The scene consists of a trail of blood about 75 feet long, starting on Frankford Avenue and it goes west into the 2000 block of East Stella Street. We don't have a motive for the stabbing, we don't have a description of a perpetrator or perpetrators."
Detectives did interview the men that tried to help the woman. Now police are looking at surveillance cameras in the area hoping they yield something.