It happened in the parking lot of a strip mall on Route 9W in West Haverstraw.
A witness said he thought what he believed to be a cat screeching and ran outside to see the man repeatedly stabbing the woman with a large knife, possibly 12 inches in length.
"She was on the floor, and she was bleeding over there," witness Mike Sabino said. "Repeatedly stabbed. I kind of caught it towards the end, where he saw people were coming and he took off."
Surveillance obtained exclusively by WABC-TV shows the man chasing the woman into the parking lot, while a pair of bystanders watched. Then, he attacks her and begins stabbing.
Several people ran outside when the woman began screaming, and they say the suspect dropped the weapon and ran.
"When I looked out my window, I could see him just going like this (makes stabbing motion), and she was trying to cover herself," witness Dorrie Peralta said. "I just started screaming."
Peralta said she was treating the victim in the parking lot, when the victim told her the suspect was the father of her baby.
Other witnesses gave chase, even hopping a fence after the suspect. Police arrived and took him into custody, according to the witnesses.
The suspect, 23-year-old Anthony Russell, is facing multiple charges, including attempted murder and assault.
The victim was taken to the hospital where she was listed in critical but stable condition.
Police determined that it was a domestic related incident as the victim has an active order of protection against Russell.