Unarmed man shot in Philadelphia by on-duty detective fearing he would be robbed: Police

Police in Philadelphia are investigating an officer-involved shooting in which a plainclothes, on-duty detective traveling in an unmarked police car fired on an unarmed man who he believed was pointing a gun at him.

The shooting occurred on Monday around 8:45 p.m., police said in a news release.

The detective, who police identified as a 29-year-old who joined the department in October 2011, was stopped in traffic near the intersection of G Street and Tioga Street when he saw the man yelling in the street "with his arms extended forward and his hands together."

Surveillance video obtained by ABC News showed the man, identified by family as 28-year-old Joel Johnson, walking in between cars stopped in the street. As he moves toward a car, smoke suddenly can be seen and Johnson falls to the ground.

The detective believed that the man had intended to rob him and fired his gun at the man four times "from inside" his car, police said. The man, who was struck in the stomach, was taken to a hospital and is currently in critical, but stable condition, police said.

Johnson's niece, Ashley Tirado, said that her uncle came to the area every day and that everyone knew him because he asked for change.

"Why does he deserve this? He stays to himself. He begs for money and just goes home," Tirado told ABC station WPVI-TV in Philadelphia.

No gun was found on Johnson or at the scene, police said.

"It's not automatically an issue of whether there's a weapon or not -- and I know for some people, they think that's the way it should be," Police Commissioner Richard Ross told WPVI-TV. "Obviously it's the first thing we look for but, I mean, I'm always going to be very candid with you. And, I know there's not one [weapon]. And so I'm not going to sit here and tell you that, you know, we have't found one. We don't expect to find one."

Police are still investigating the incident. \

The officer was a seven-year veteran and has been placed on desk duty, which is protocol during investigations, according to WPVI-TV.