Police told teens several times to get out of a stolen car before opening fire and killing the 17-year-old girl behind the wheel as she drove at one of the officers, Denver's police chief said.

The officer was between the car and a brick wall and felt threatened as he and a colleague opened fire, killing Jessica Hernandez, Chief Robert White, citing preliminary information, told The Denver Post in a story Thursday.

White said he cannot judge whether the officers acted appropriately until criminal and internal investigations are completed.

"Like I said the morning of the incident, there are a lot of unanswered questions," he told the newspaper..

A passenger in the car, who spoke on the condition of anonymity because of safety concerns, has disputed the official account of the shooting, saying officers came up to the car from behind and fired four times into the driver's side window.

Hernandez's mother said she wants a second, independent autopsy because she doesn't trust the official investigation into the death of her daughter.

"I want another autopsy on my daughter so we can know how much damage they did," Laura Sonya Rosales Hernandez, speaking in Spanish, told The Associated Press.

"I want to know, how did this happen? I want to know everything." the mother said inside the trailer home where her daughter lived with five siblings.

The shooting occurred amid a national debate about officers' use of force fueled by killings in Ferguson, Missouri, and New York City.

It was the fourth time in seven months that a Denver officer shot at a vehicle after perceiving it as a threat.

The U.S. Supreme Court has said that officers may not use deadly force to stop a fleeing suspect unless the person is believed to pose significant physical harm. Still, policies vary among agencies, and some departments have banned or discouraged the practice.

The Albuquerque Police Department, for example, ordered officers in June to stop shooting at moving vehicles after a U.S. Justice Department report found a pattern of excessive force.

In Denver, the police department and independent monitor Nicholas Mitchell separately are looking at how national standards compare to Denver's policy, which allows officers to fire at moving cars if they have no other reasonable way to prevent death or serious injury.

Denver's policy says, "An officer threatened by an oncoming vehicle shall, if feasible, move out of the way rather than discharging a firearm."

The reviews will look at several cases, including the fatal shooting of Ryan Ronquillo, 21, who police said tried to hit them with his car outside a funeral home in July.

Experts say shooting and disabling a driver can send a car out of control.

"If you were to shoot at the driver, you would have an unguided missile, basically," said Chuck Wexler, executive director of the Police Executive Research Forum, which suggests departments forbid officers from shooting at moving vehicles unless there is another deadly threat involved, such as a weapon.

Police identified the officers in the Hernandez shooting as Daniel Greene, a 16-year-veteran, and Gabriel Jordan, a nine-year veteran. Hours after their names were released Wednesday, a group gathered outside the police station calling for justice.

Jordan suffered a fractured leg, department spokesman Sonny Jackson said, declining to comment further about details of the case.

Hernandez's mother said her daughter made a mistake by "grabbing" a car that did not belong to her but didn't deserve to pay with her life.

"How much do they need to investigate?" she asked. "It's all done. They did it. They killed her. All I want is justice."

The passenger in the car, who spoke on the condition of anonymity because of safety concerns, said Hernandez lost control of the vehicle because she was unconscious after being shot.