Sgt. Justin Farley told KRMG at the scene that the man confronted the woman and two men as they were stealing items from a silver Chrysler Pacifica.
During that confrontation, the woman came up from behind and stabbed the victim in the back with a knife.
Farley says it appears they were in the pawn shop earlier, and detectives have surveillance video of them.
He was taken to the hospital with a non-life threatening wound.
Officers searched for the trio, who apparently left on foot -- though police believe they may have had a vehicle nearby.
He also said police already think they know the identities of the suspects.
They did apparently get away with some items from the vehicle, including a GPS unit.
Police say the man had left the car unlocked when he went into the pawn shop.