PEORIA, Ariz. - Chaos ensued on a Phoenix freeway on Friday morning after a car crashed off the side of the road. As witnesses pulled over to help, they saw a man stabbing a woman to death.

cellphone video from another driver shows a man appearing to stab a person next to the car, while witnesses scream for help. In the video obtained by our TEGNA sister-station 12 News, six gunshots can then be heard as the subject falls to the ground.

The man, identified as 25-year-old Fernando Acosta of Phoenix, is expected to survive those shots, but a San Diego woman at the scene did not survive several stab wounds.

Acosta was booked into the Fourth Avenue Jail on charges of first-degree murder and aggravated assault. 

According to DPS, investigators are not sure yet what led to the crash. Officials said immediately after the car crash, there was an altercation between Acosta and the woman who was in her 30s.

Witnesses can be heard yelling, “He’s killing someone,” and “get away from her,” but all of them are on the other side of a canal from the scene.

"I wish I could've done more to help," said Gustavo Munoz, one of the witnesses. 

Munoz was one of the people who pulled over to help, but he soon feared for his own life.

"When I got to the other side of the ditch, the guy comes out with a knife saying, 'What the f*** do you want? What the f*** do you want?' And the lady was in the passenger side filled with blood already," Munoz said. 

Arizona DPS gives news briefing about the crash and stabbing

After the suspect was shot, Munoz and the others moved in.

"I put my knee on his back, got his hands so he couldn't move. He was moving like crazy, and laughing while he was doing it," Munoz said. "That's when we took a couple hits to his face. We hit him so he can stop, but he was like, 'Do it again, do it again,' and he was just laughing." 

"We're grateful that nobody else was hurt—no bystanders," DPS spokesman Kameron Lee said.

DPS has not yet given information about the shooting that may have stopped the suspect, who Munoz says is a sadistic criminal. 

"It looked like he didn't care at all. He was just going at it," Munoz said. 

DPS detectives are still investigating all aspects of the incident and interviewing witnesses.