A Philadelphia police officer who fatally shot a 12-year-old boy after the boy allegedly fired into an unmarked police car and fled on foot will be fired, authorities said Tuesday.

Police Commissioner Danielle Outlaw announced that the officer will be suspended for 30 days, starting Friday, after which she intends to dismiss him for violating the department’s “use-of-force directive.”

“Based off of the evidence that I reviewed, it was clear that the use-of-force policy was violated,” Outlaw said during a press briefing.

The officer was one of four plainclothes officers in an unmarked car conducting surveillance in South Philadelphia on March 1 shortly before 7:30 p.m. when the shooting occurred, police said.

The officers approached two juveniles — a 17-year-old boy who they wanted to question and the 12-year-old boy — with the car’s emergency lights on, according to Outlaw.

The younger boy allegedly fired at the car, striking the passenger side rear window, police said. One of the officers was struck in the eye by glass after a bullet went through the car’s window, police said.

Two other officers then returned gunfire, shooting once each, before the suspect fled on foot with the firearm, Outlaw said. An officer gave chase and fired his gun twice, striking the boy in the back, she said.

The 12-year-old boy, identified by authorities as Thomas Siderio, was pronounced dead at a nearby hospital, police said.

“It’s tragic that we have trigger-pullers as young as 12,” said Outlaw. “And it’s tragic that we had one of our own, again, go against everything who we say we are. There are no winners here.”

None of the four officers have been identified by the department due to safety concerns, the commissioner said.

The officers were placed on administrative duty following the shooting, police said. The department did not have any further information Tuesday on the status of the other officers due to the ongoing investigation.

The 17-year-old was taken into custody following the shooting. He was later released and not charged, Outlaw said.

The Philadelphia District Attorney’s Office is conducting a criminal investigation into the shooting. No charges have been filed at this time.

“The death of a child is always a tragedy, and in this instance, a factually complex and deeply troubling one based on preliminary investigative information,” District Attorney Larry Krasner said in a statement.

“Philadelphians are owed a comprehensive and transparent accounting of all activity surrounding the circumstances of young Thomas Siderio’s death and an unbiased and thorough investigation,” he continued. “When it is appropriate for us to do so, we will disclose findings of our currently active investigation and decision on whether or not to pursue any criminal charges.”

Siderio’s family filed a civil lawsuit against the four officers involved in the shooting on Thursday, their attorney, Conor Corcoran, told ABC News.

“This 12 year old was murdered at point blank range by a Philadelphia police officer,” he said in an email to ABC News.

He said the commissioner was “correct” in firing the officer in question, but disputed that the boy had a gun.

“They are claiming that young TJ possessed or fired a gun, when my information indicates that the body still has its fingernails, and so no gunpowder residue testing was performed,” Corcoran said.