Three days after he killed an unarmed 15-year-old boy, a Balch Springs police officer was fired.

"From our policies, which I went by, there were violations. I acted on them," Balch Springs Police Chief Jonathan Haber said Tuesday evening.

Officer Roy Oliver shot his rifle into a vehicle full of teenagers Saturday night as they were driving away from a party. Jordan Edwards was fatally struck in the head, with his brothers beside him in the vehicle.

Although the department said its internal investigation had concluded, the chief refused to detail Oliver's policy violations, citing the officer's right to appeal his termination and ongoing inquiries by the Dallas Sheriff's Department and the Dallas County district attorney's public integrity unit.

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"You have my assurances my department will continue to be responsive, transparent and accountable," Haber said.

Attorney Cindy Stormer, a former prosecutor who is representing Oliver, asked the public to be patient while the six-year veteran of the department is investigated.

"We cannot make any comments at this time," she said in a written statement. "The incident is recent and still being investigated. Everyone should wait until the facts come out and we know more."

Jordan is the youngest of 333 people shot and killed by police in the United States so far in 2017, according to The Washington Post, which is tracking police shootings nationwide. In 2016, according to the Post, 963 people were shot and killed by police. In 2015, the number was 991.

Sgt. Jon Craker of the Balch Springs Police Association declined to comment on Oliver, saying the chief had instructed officers not to speak publicly about the case.

Even before Oliver, who is white, was publicly

Tuesday, the killing of an unarmed black teenager had stirred allegations of prejudice familiar from other fatal police shootings nationwide.

Eight out of 10 Balch Springs police officers are white -- though four out of five residents are not.

Oliver became a peace officer in 2010, first in Dalworthington Gardens near Fort Worth, according to the Texas Commission on Law Enforcement. He joined Balch Springs' Police Department in 2011. His most recent training was a firearms course April 22 at the police department. He has also taken classes called Precision Rifle, Less Lethal Electronic Control Device Training and Use of Force.

Oliver served in the Army and was on active duty from 2004 to 2010, according to the Department of Defense. He served at least one tour in Iraq.

Jordan's relatives expressed gratitude that Oliver had been fired but said in a written statement, "There remains a long road ahead." They want Oliver arrested on a murder charge, and they hope other officers involved in the case will be held accountable.

"After Jordan's two brothers, Vidal and Kevon, along with their two friends, were forced to experience this tragedy up close as occupants of the car, they were immediately treated as common criminals by other officers; manhandled, intimidated and arrested, while their brother lay dying in the front seat," the family said. "The officers who extended this nightmare for those children ought to be properly reprimanded."

However, the family has asked people not to stage protests in Jordan's name as they prepare for his funeral, which is planned for Saturday.

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Accounts change

Oliver was the second of two officers who responded to a report of intoxicated teenagers before Jordan was shot, the department said. Police had gone inside a house where a party was underway when they heard gunshots and ran outside.

Jordan Edwards

The police chief said Tuesday that he had relied on Oliver's account of events when he initially said the vehicle was moving toward officers aggressively.

That's "my inability to get all the facts like I should have," Haber said. "... That was solely on me. In a rush to get the information out, to be transparent ... I missed a step."

Brother held overnight

An attorney for Jordan's family, Lee Merritt, told NBC News that Jordan's older brother, who was in the vehicle, was handcuffed and held overnight. Although police later said they kept the brother in custody to question him as a witness, none of the other teens were held, he said.

Meritt said police also detained Jordan's father when he showed up at the station asking about his children.

"Balch Springs PD called the Dallas County Sheriff's Office and asked if they could restrain Jordan's father because of his hostile behavior," he said.

Merritt said Jordan and four other teenagers had gotten into the vehicle to leave after they heard gunfire. As they were pulling away, they heard someone cursing before three shots were fired into the vehicle.

"They witnessed firsthand his violent, senseless, murder," Jordan's family said in a statement before Oliver's firing. "Their young lives will forever be altered. No one, let alone young children, should witness such horrific, unexplainable, violence."

The Texas Legislative Black Caucus issued a statement saying no one "in retreat who has not been accused of a crime should be shot with a rifle."

"Once again our nation has been gripped with the death of an unarmed African-American teenager after what seemingly appeared to be the aggressive tactics of a law enforcement official," said Democrat Helen Giddings, who represents Dallas and is a member of the legislative caucus. "While the investigation is still ongoing, we must face the fact that we have lost another young black male at the hands of a law enforcement official."

Staff writers Eline de Bruijn, Claire Cardona, Naheed Rajwani, Sarah Mervosh, Terri Langford and Tom Steele contributed to this report.