It happened around 10:00 a.m. in the 4800 block of McKean Avenue in the area of Logan Street.
The victim in this case is described as an older female dog that would rather watch the squirrels than chase them.
"Two brownish-color pit bulls came into the park out of nowhere and just attacked her," said witness Nicole James. "We can hear her crying and being brutally attacked."
James said she did not see an owner for the dogs.
"I immediately pulled out my phone and dialed 911 to tell them that there are two pit bulls attacking a dog."
James, who owns a pit bull herself, said her first instinct was to throw rocks at the attacking dogs. The off-duty officer cautioned her that it was too dangerous.
Instead, they flagged-down an on-duty police officer.
"They charged the cop. The cop pulled out his gun and shot three times and the third one put him down," said James. "There was no other way he could have got the dog. There was no mace that would have stopped that dog, there was no commands that would have stopped that dog."
"They were out of control."
There was a large police presence at the scene because that 39th District police officer fired his gun, so there must be an investigation.
The dog that was attacked was taken to the University of Pennsylvania Veterinary Hospital.
As for the attacking dogs, one was killed while the other got away. Police say they have located the owner, however there was no word on any charges so far.