Mona Rodriguez was fighting with a 15-year-old girl one afternoon late last month about a block from a Long Beach, Calif., high school when a police officer who was driving by stopped and tried to break up the scrap by threatening to pepper-spray them.

The de-escalation tactic worked. The two stopped.

Then, Rodriguez got into the front passenger seat of a gray car driven by her boyfriend. Bystander video shows the school safety officer, Eddie F. Gonzalez, put his hands on the passenger side and shouted “Hey!” while the four-door sedan peeled out. As the car passed him, Gonzalez fired twice.

One of the bullets hit Rodriguez in the head, leaving the 18-year-old mother brain-dead.

Over the next week and a half, an uproar grew as Rodriguez clung to life at a hospital. The city’s mayor called the shooting “horrific and tragic.” Her family called on prosecutors to criminally charge the officer and, through a lawyer, pushed the California attorney general to open his own investigation.

On Tuesday, eight days after the shooting, Rodriguez died when her family took her off life support. The next evening, the Long Beach Unified School District’s board voted unanimously to fire Gonzalez, who had been hired in January after short stints at several police departments, saying he violated the district’s use-of-force policy. A district spokesperson told CNN that Rodriguez was not a student in the district but had been previously.

On Thursday, Long Beach Police Department detectives opened a homicide investigation, noting Gonzalez was employed by the school district, not the city. Police will pass their findings to the Los Angeles County district attorney’s office, which will decide whether to charge the officer and with what, a department spokeswoman told The Washington Post.

Efforts to reach Gonzalez were unsuccessful. It is not immediately clear whether he has hired an attorney.

As the Long Beach school board met Wednesday night, dozens gathered outside, with many calling for the district to take all officers out of schools or to require more de-escalation training. People cheered when someone announced the board’s decision to fire Gonzalez, but Rodriguez’s older brother, 23-year-old Oscar Rodriguez, said it was only “a first step.”

“I hope my sister gets the justice that she deserves,” he told the crowd earlier in the evening, the Los Angeles Times reported. “This can happen to any other family next.”

The district’s use-of-force policy, obtained by The Post, allows officers to fire their guns only in self-defense or to prevent the death or “great bodily injury” of another. It forbids them from firing at someone who is fleeing, toward a moving vehicle or through a vehicle window, unless circumstances “clearly warrant the use of a firearm as a final means of defense.”

Board members decided those leading to Rodriguez’s death didn’t.

“We clearly saw areas where this employee violated District policy, and did not meet our expectations. We believe the decision to terminate this officer’s employment is warranted, justified, and quite frankly, the right thing to do,” Long Beach Unified School District Superintendent Jill Baker said in a statement provided to The Post.

Luis Carrillo, the lawyer representing the Rodriguez family, wrote a Sept. 29 letter to California Attorney General Rob Bonta, asking his office to investigate what he called an unjustified shooting. The officer took “reckless action” and met “the threshold for criminal charges against the officer for murder or for manslaughter,” Carrillo wrote in his letter.

“Everybody is upset that a rogue officer did this ugly thing that he did — shot at an 18-year-old young lady — and is still walking the streets. This officer should be in jail right now,” Carrillo told reporters.

Cheryl Dorsey, a retired Los Angeles Police Department sergeant, told CNN she watched the bystander video of the shooting and agreed that the actions were not justified under police policy.

“There is no imminent threat to that officer or anyone else as they’re seated in a vehicle and driving away. Get a license plate number — there were so many other options tactically available.”