‘No justification’ for officer charged with homicide in killing of unarmed teen, prosecutor says Officer Michael Rosfeld has been charged with criminal homicide.

The Pittsburgh-area police officer who shot and killed an unarmed teenager last week has been charged in his death, with prosecutors calling the killing an “intentional act.”

The officer, identified by authorities as Michael Rosfeld of the East Pittsburgh Police Department, was arrested and arraigned on one count of criminal homicide Wednesday morning, according to court documents obtained by ABC News. He is scheduled to appear before a judge for a preliminary hearing July 6.

An attorney for Rosfeld told ABC News in an interview Wednesday that he's not surprised by the charge but his client is "devastated" by what happened and is seeking counseling. The officer, who has been placed on unpaid leave, was released from jail after posting bond Wednesday, his attorney said.

Rosfeld fatally shot 17-year-old Antwon Rose in the borough of East Pittsburgh on the night of June 19, after the teen and two others were pulled over in a car believed to have been connected to a drive-by shooting earlier that night in the nearby borough of North Braddock.

Pat Thomassey, Rosfeld's attorney, told ABC News his client had reasonable belief that the individuals in the car had been involved in a serious crime, citing the vehicle's busted windows, so he fired his gun when the suspects fled.

But Allegheny County District Attorney Stephen Zappala said Rosfeld intentionally shot Rose to death, even though the teen "didn't do anything in furtherance" of a crime in North Braddock or East Pittsburgh.

"It's an intentional act and there's no justification for it," Zappala said during a news conference Wednesday. "You do not shoot somebody in the back if they are not a threat to you."

Allegheny County prosecutors argued "vigorously" that Rosfeld should be denied bail because the charge carries a maximum sentence of life imprisonment. But they were overruled by the magisterial district judges presiding over the case.

"Somebody's dead. Can there be any more dangerous [of a] situation?" Zappala told reporters.

The charge of criminal homicide is defined in the affidavit as any instance in which someone intentionally, knowingly, recklessly or negligently causes the death of another human being. Zappala said "there's no doubt" that the evidence in the case against Rosfeld supports a third-degree murder charge.

"We think we should have the right to argue murder in the first degree," he said. "I find that Rosfeld’s actions were intentional and they certainly brought about the result that he was looking to accomplish.

“He was not acting to prevent death or serious bodily injury. It’s my position that he is not entitled to a justification charge to a jury as a defense."

Zappala said Rosefeld should have waited for backup after apprehending the driver, instead of instructing all passengers to exit the vehicle during the traffic stop in East Pittsburgh, about 11 miles southeast of downtown Pittsburgh.

Rose was struck three times from behind as he and another passenger fled on foot from Rosfeld. The Allegheny County Medical Examiner has ruled Rose's death a homicide.

Zappala said "neither of these young men were in possession of a weapon" when they were fleeing.

"There was no weapon that created a risk to Officer Rosfeld," the district attorney told reporters Wednesday.

Fred and Monte Rabner, two of the attorneys representing Rose's family, released a statement Wednesday morning reacting to the criminal homicide charge filed against Rosfeld.

"The Rose family views the filing of criminal homicide charges with guarded optimism,” the attorneys said in the statement. “There is a long road ahead to a conviction and proper sentencing which is the only thing we will accept as justice.”

Rose's family is "devastated" and "stunned" by his death, Fred Rabner told ABC News in an interview last Thursday.

The attorney described Rose as a "beautiful, kind" and hard-working teenager who worked with young children at a gymnastics gym, as well as at a Domino's Pizza location.

His funeral was Monday.

Zappala, the district attorney, told reporters he spoke with Rose's family Wednesday morning, just before the news conference.

"They're wonderful people," he said of the family. "Obviously, they're very distraught by the loss of their son."

Rose's mother, Michelle Kenney, was too distraught to speak during an on-camera interview with ABC News after the news conference Wednesday. Kenney's attorneys, who were at her side, spoke on her behalf, telling ABC News how she felt a "huge sigh of relief" when the district attorney announced the charge against Rosfeld. But it’s the first step in what will be a long process, they said.

"We need to get to the point where we stop looking at the victim to try to find something about him to rationalize a senseless act of violence," Fred Rabner told ABC News.

Rosfeld, 30, had been on the job as an East Pittsburgh police officer for three weeks and was formally sworn in just hours before the deadly shooting happened. The Allegheny County Police Department is leading the investigation into the incident.

Detectives who interviewed Rosfeld, alongside his attorney, said they noticed an inconsistency in his account of what happened, according to the affidavit.

The officer allegedly told detectives that when the front-seat passenger emerged from the vehicle, the individual turned his hand toward Rosfeld, who saw something dark that he perceived as a gun. This caused him to fire his weapon, according to the affidavit.

But when detectives asked Rosfeld to go over the sequence of events again, the officer allegedly told them he didn't see a gun when the passenger exited the vehicle and ran. Detectives confronted him with the inconsistency, and Rosfeld allegedly stated that he saw something in the passenger's hand but was unsure what it was.

Rosfeld also allegedly stated that he was unsure whether the individual who had his hand pointed at him was still pointing at him when he fired the shots, according to the affidavit.

Zappala said Rosfeld appeared "remorseful" during the interview with detectives.

The shooting was captured by a bystander on cellphone video, which is being reviewed by authorities.

During an off-camera interview Thursday with ABC Pittsburgh affiliate WTAE, Rosfeld said he didn't know there was video showing the moment he fired his gun at Rose. He also said he and his family are struggling to cope but have received much support from law enforcement.

Rosfeld told WTAE he wasn’t ready to talk about what happened in the moments before he fired his gun or why he did it.

Two guns were recovered from the light-gold Chevrolet Cruze from which Rose and the other passenger fled June 19: a 9 mm Glock pistol under the front portion of the passenger seat that had been reported lost that day in Monroeville, Pennsylvania, and a .40-caliber Glock pistol under the rear portion of the front passenger seat that had been reported stolen in 2016 in Lower Burrell, Pennsylvania, according to the affidavit.

An examination of the firearms by the Allegheny County Medical Examiner's crime laboratory determined that the spent casings recovered from the scene of the June 19 drive-by shooting in North Braddock were fired from the stolen .40-caliber pistol found in the Chevrolet Cruze in East Pittsburgh.

Detectives determined that Zaijuan Hester, 17, was the individual who fired the .40-caliber pistol from the Chevrolet Cruze in the drive-by shooting that preceded Rose's killing. Hester was arrested and charged Wednesday morning for aggravated assault, criminal homicide, receiving stolen property and firearm charges, according to WTAE. He is being held at the Shuman Juvenile Detention Center.

Rose was not armed when he was shot, authorities said. But an empty gun magazine was discovered in his right-front pocket that fit the 9 mm pistol found in the Chevrolet Cruze, according to the affidavit.

"Antwon didn't do anything in North Braddock other than be in that vehicle," Zappala told reporters Wednesday. "Antwon did not fire a gun at all ... the 9 mm was never discharged."

Protests condemning Rose's killing have consumed downtown Pittsburgh in the days after the shooting.

During a rally Thursday, one protester read a now-haunting poem written by Rose in 2016.

"I see mothers bury their sons," the poem says. "I want my mom to never feel that pain."

ABC News' Armando Garcia, Jennifer Leong, Dominick Proto and Emily Shapiro contributed to this report.

Editor’s note: Police officer Michael Rosfeld’s affiliation was misidentified in an earlier version of this story. He works for the East Pittsburgh Police Department.