PHILADELPHIA >> A plainclothes Philadelphia police officer fatally shot a 12-year-old boy in the back Tuesday night, moments after a bullet was fired into an unmarked car, police said.

Police identified the youth as Thomas Siderio Jr., saying officers took him to Penn Presbyterian Medical Center where he was pronounced dead a few minutes after the shooting. The police statement Wednesday described Siderio as white.

One of the four officers in the car was struck by shattered glass in the face and eye, and was treated and released, police said.

In a statement Wednesday, police said the four officers wearing plainclothes were in an unmarked car in south Philadelphia at about 7:20 p.m. Tuesday as part of a task force responding to social media posts involving a gun. The officers said they saw two young males on a corner — one of whom appeared to be carrying a handgun — and recognized the older one as someone wanted for questioning in that firearms investigation.

The officers activated the car’s emergency red and blue lights and then heard a gunshot and the rear passenger window shattering, police said.

Deputy Commissioner Benjamin Naish said the bullet went through the window, ricocheted off the passenger door and went through the passenger-side headrest, saying the officers very easily could have been killed or seriously injured. He spoke during a virtual update on gun violence in the city Wednesday.

Police said two officers got out of the driver’s side of the car and fired at the fleeing youth, who officers said was holding a gun. One of the officers continued to chase Siderio down the street, firing two more times and striking the boy once in the upper right back area. The bullet exited through his chest, police said.

The other youth, a 17-year-old male who was not named, was taken into custody in the firearms case but was later released, police said.

Naish said officers recovered a 9mm semiautomatic handgun equipped with a laser that had been reported stolen. He said the gun had one bullet in the chamber and five more in the clip.

Naish said police could not definitively say Wednesday that Siderio had shot into the police vehicle, or whether he had pointed the weapon at officers as he fled.

Police also did not say whether the recovered gun was part of the initial investigation.

“While the indications from the medical examiner is that the bullet entered into his back, that does not mean he was fleeing or that there was not a gun being pointed toward or in the vicinity of the officer. It doesn’t mean that he wasn’t continuing to be a threat to the officer,” Naish said.

He said ballistics evidence had been gathered and police were scouring the area for surveillance footage as part of the investigation. None of the plainclothes officers was wearing a body camera, he said.

The two officers who fired their weapons were placed on administrative leave pending an investigation.