The family of a 17-year-old girl shot and killed by a Southern California police officer is demanding answers about the deadly Friday night shooting.

The incident occurred in Anaheim. The Anaheim Police Department said in a news release that a Fullerton Police K-9 officer radioed around 7 p.m. that he had been involved in a shooting on the freeway.

"A female suspect was struck by gunfire and was transported to a local hospital where she later died," Anaheim police said.

No officers were injured during the shooting, police tweeted.

Police did not name the girl who died, but family members identified her as Hannah Williams.

According to police, an "item appearing to be a handgun was recovered at the scene."

The Orange County District Attorney's Office said in a press release Tuesday that the Fullerton officer was taking his K-9 to a veterinarian for a procedure when he encountered the teenager. The prosecutor's office also said that the item appearing to be a gun was a fake.

"The officer-involved shooting occurred and what appeared to be a Beretta 92 FS handgun was recovered at the scene next to the female," the press release said. "The gun was later identified as a replica handgun designed to look like a handgun."

But Rev. Jarrett Maupin, a spokesman for the family, told NBC News on Tuesday that Hannah did not have a gun on her when she was shot.

"We maintain that she was unarmed, a fake gun is a fake gun," Maupin said during a press conference Tuesday.

Maupin said they still did not know details on how Hannah died, such as how many times she was shot or even where she was shot. The family is now asking for the officer to be suspended without pay and for California Gov. Gavin Newsom to open a state investigation into her death.

"An independent umbrella investigation by the [attorney general] would go a long way to making sure we’re keeping local authorities honest," Maupin said.

There will be an independent autopsy, as requested by the family, once Hannah's body is released by the county, Maupin said.

Lynette Campbell, Hannah's godmother, read a statement to reporters on behalf of the family Tuesday.

"Losing Hannah is hard. The circumstances in which we lost her make it that much harder," the statement said. "As of today we still do not have clear answers as to what happened to Hannah. The information that we have received from the police department has changed several times."

Details leading up to the shooting are scarce. According to KTLA, initial reports indicate that the Fullerton officer's police car had been struck by another vehicle moments before the shooting.

Maupin said Hannah, who worked as a lifeguard, spent Friday with her family at their home in Anaheim before leaving that evening. He referred to an accident involving a shared rental car driven by Hannah, but said it was "very minor."

Hannah, who had moved from Phoenix to the area less than a year ago with her family, was about two miles from home when the shooting occurred. Anaheim police said more information may be released this week after potential witnesses are interviewed.

"The freeway was packed and all potential witnesses need to be interviewed first. We cannot risk influencing someone's statement, by releasing details prematurely," the department tweeted.

The Fullerton PD did not return NBC News' request for comment.