PEORIA, Ariz. — A 25-year-old Arizona man who was driving a San Diego-area woman’s car is accused of fatally stabbing her after the vehicle veered off a freeway and crashed in a Phoenix suburb, resulting in a chaotic scene involving passers-by who stopped to help.

Fernando Acosta of Phoenix got out of the car and accosted a witness with a knife before repeatedly stabbing Martha Thy of Spring Valley, California, along the Loop 101 freeway in Peoria on Friday, according to an Arizona Department of Public Safety probable-cause statement released Saturday.

Thy was stabbed while she was still inside the white Lexus sedan and then while on her knees on the ground outside it after she crawled out and closed a door behind her, the statement said

Acosta initially was on the driver’s seat when he began stabbing Thy, who was seated in the passenger seat, the statement said. He then got out of the driver’s side of the vehicle, going around to the passenger’s side and resuming stabbing Thy before returning to the driver’s side when she attempted to get away, the statement said.

Thy died at a hospital. The statement she was stabbed or cut at least 20 times.

The statement did not mention a possible motive. No additional information was available, the Department of Public Safety said Saturday.

Acosta remained jailed Saturday on suspicion of premeditated first-degree murder and aggravated assault. Court records don’t list an attorney who could comment on his behalf regarding the allegations.

Several people stopped to help the woman, the Department of Public Safety said.

Gustavo Munoz told KNXV-TV that he was among the passers-by who stopped and jumped out of his car to help. “I ran towards the vehicle, and when I got to the other side of the ditch the man comes out with a knife. Hands full of blood. (His) face, body was filled with blood,” Munz said.

A man with a gun fired shots at the ground to try to scare the attacker “to see if he would drop the knife and stop stabbing the lady that was in the vehicle,” Munoz said.

One of the passers-by eventually tackled the suspect and knocked the knife from his hands, and others piled on and held the man down until police arrived, Munoz said.

Responding officers encountered a chaotic scene, Department of Public Safety spokesman Trooper Kameron Lee said. “People everywhere, some screaming, yelling going on, so you can only imagine what an officer’s feeling when he arrives on scene and all he sees are people running around,” Lee told azfamily.com.

It was tragic that the woman was killed, but authorities are grateful that none of passers-by were injured, Lee said.

Northbound lanes of the freeway were closed in the area of the incident for much of Friday as Department of Public Safety detectives conducted their investigation.