Irving police released unedited surveillance video Friday that shows a woman being attacked as she worked out at a local gym.
In the video, the woman can be seen near the top right of the frame working out on a treadmill as a person approaches.
While the stabbing isn't clearly visible in the video, the person can be seen moving toward the woman on the treadmill and then people around her rush to her aid. She can then be seen being brought to the front desk where she is surrounded by people as they wait for an ambulance.
The victim, whose name has not been released, sustained three puncture wounds to her back and shoulder, and was rushed to Parkland Memorial Hospital in Dallas for treatment. She is expected to survive.
The man identified by police as the woman's attacker, 32-year-old Phillip Roberts, told NBC 5 in a jailhouse interview that he didn't know the victim and didn't remember attacking her. He said he remembered people pulling him off the woman, but not what led to the attack.
"My thought pattern is, I really, I can't remember on the first part of it. I remember when I came conscious of a certain thing. I'm conscious of the end, when they're pulling me off and different things of that nature. I'm conscious of that," Roberts told NBC 5.
Roberts was taken to the Dallas County Jail Tuesday evening and was to be charged with aggravated assault with a deadly weapon.
NBC 5's Jocelyn Lockwood contributed to this report.