a police officer routinel routiy driving along notices a fight between a man and his girl forty seven that. girlfriend police say is wielding a knife. as the officer gets out of his cruiser an items to enter 15, there's a struggle and police say the woman cuts the officer. >> any time we respond to an incident of a domestic incident or just on patrol, you never know what's going to happen. >> reporter: that officer injured was still able to apprehend the man and the woman. >> these officers are trained to respond to whatever situation they may have coming toward them and in this instant the officer did an out staning john and affected the rest of the individuals. >> reporter: the officer was taken to the hospital with only superficial wounds sliced once in the arm. he'll be okay much police say thanks to his training and a little bit of luck. >> any day that we can get lucky philadelphia police officers we consider that blessing. >> reporter: meanwhile, police have not yet identified either of the people who were arrested or the charges that they face. this investigation is on going t