PHILADELPHIA (CBS) — A detective shot a man who he thought was armed as he came towards his car in Kensington Monday night, police say. The incident unfolded on the 3400 block of G Street shortly before 9 p.m. Police have confirmed the man was unarmed.

According to police, the plainclothes detective had just left the scene of another incident and was stopped at a red light in an unmarked vehicle, when a 28-year-old special needs man emerged from between two parked cars on the officer’s driver side.

Police say the man approached the unmarked police car, asking for change. The family identified the man as Joel Johnson.

#Update: Man who says he’s brother of man shot says his brother is 28yo, has mental disabilities and begs for quarters. He approached detective’s car asking for money and brother says startled the officer who fired through window and hit brother. — Greg Argos (@GregArgosCBS3) May 21, 2019

The officer believed Johnson was speaking to him, but he could not hear what was being said, police say. According to authorities, the officer believed he saw a firearm in the man’s hand, at which time, the officer shot three times, shattering the car’s window and striking Johnson once in the torso.

“The detective believed what he saw was a firearm in this male’s hand,” Capt. Sekou Kinebrew said. “The detective, believing he was going to be robbed or something was going to happen to him, produced his firearm.”

13-Year-Old Boy Rushed To Hospital After Being Shot In Kensington, Police Say

Johnson was transported to Temple University Hospital, where he is now in critical but stable condition, according to police.

“My little brother came up to the police car, asking for change, for a quarter … and the officer was on his phone and he said he reacted, he got nervous, pulled out his weapon and just started shooting through the window,” the victim’s brother, Hector Tirado, said.

The investigation is now revealing Johnson did not have a gun.

“I’m not going to sit here and say we haven’t found one, we don’t expect to find one,” Philadelphia Police Commissioner Richard Ross said.

The officer was not harmed.

A resident who lives just feet away from the shooting saw Johnson gesturing for money.

“He could have shot my granddaughter, or my daughter, or wife,” a resident said. “This man is out here every day from 9 in the morning to like 6, 7 or 8 at night begging for quarters. We feed him. He is innocent.”

Police say the officer involved is a seven-and-a-half-year veteran of the force, assigned to East Detectives. The detective is on desk duty while police investigate whether this was a justifiable shooting.

CBS3 reporter Greg Argos contributed to this report.