It happened around 4:00 Friday afternoon on the 2800 block of Arthur Avenue.
Authorities say a 21-year-old autistic man, identified by family as Louis, was getting off a bus when he screamed and ran toward a home across the street.
A male caretaker ran after him as Louis began banging on the door of an off-duty officer's home.
The officer told investigators he thought someone was trying to break in and fired his gun. The bullet went through the front door, striking the Louis in the arm and also wounding his caretaker.
"Just to shoot through the door like that I don't think it's right," said Hector Medina, victim's brother.
Medina thinks his neighbor was too quick to pull the trigger on his brother, who is notorious for frequenting his neighbors' homes.
"We've lived on this block for 17 years with that same neighbor, he knows better than that, no excuses for it," said Medina.
Neighbors are also surprised by what happened.
"I was kind of disappointed he didn't look through the window," said Mary Cortes.
"It's an unfortunate event, it's shocking," said Nyemah Gillespie.
Gillespie says she's known Louis for nearly 20 years, he's like family, he's harmless but she also says she understands how his actions could be misunderstood.
"He's very strong, very strong, he'll run upstairs his family members will come in and get him," said Gillespie.
Both victims were taken to Cooper University Hospital for treatment. Louis' injuries are said to be non-life threatening while his caretaker is listed in serious condition.
"I'm praying and hoping he's okay, it's sad to know all the man was doing was his job and now he's part of the tragedy," said Medina.
Meanwhile the Camden County Prosecutor's Office says the officer will be placed on administrative leave as part of protocol.