A passenger who was in a car when a 17-year-old girl was shot and killed by Denver police has disputed authorities' account of her death, saying officers opened fire before one of them was struck by the vehicle.

The passenger, speaking late Tuesday to The Associated Press on the condition of anonymity because of safety concerns, said her friend, Jessica Hernandez, lost control of the vehicle because she was unconscious after being shot.

Police have said the Monday morning shooting in a residential alley came after Hernandez drove a stolen vehicle into one of them.

Prosecutors on Tuesday promised a thorough probe of the shooting as a small group of angry protesters demanded swift answers and called for a special prosecutor to investigate the death.

The shooting occurred amid a national debate about police use of force fueled by racially charged episodes in Ferguson, Missouri, and New York City.

It was also the fourth time in seven months that a Denver police officer fired into a moving vehicle after perceiving it as a threat, and the city's independent police monitor now says he will investigate the department's policies and practices related to shooting at moving vehicles, which he said poses unique safety risks.

Police spokesman Sonny Jackson offered no new details about the case on Tuesday, citing the department's open investigation.

The shooting happened after an officer was called to check on a suspicious vehicle, Chief Robert White has said. A colleague arrived after the officer determined the car had been reported stolen. Police have said the two officers approached the car on foot when Hernandez drove into one of them, and they both then opened fire.

The car's passenger said police had surrounded the car in the alley, and Hernandez was trying to flee, attempting to drive around one of the squad cars.

The officers came up to the car from behind and fired four times into the driver's side window, narrowly missing others inside, the passenger said.

Hernandez wrecked the car into a fence after she was shot, according to the witness. Police said the officer suffered a leg injury for which he was treated at a hospital and released.

Officers with their guns drawn then pulled people out of the car, including Hernandez, who they handcuffed and searched.

The passenger was unaware the vehicle was stolen and provided only vague details about what the group of teenagers was doing earlier in the night.

By law, police are allowed to use force to stop and overcome the resistance of another person. They can use it to match the force and overcome it.

Both officers involved in the shooting have been placed on routine administrative leave pending the investigation.