In a small dark alley, you hear someone screaming for help, even though you were scared, but you dared to check the origin of the sound

With shock you see a tall man killing a man who was screaming earlier

don't know what stupid thing are you thinking, without warning you ran to the tall man, and grabbed him from behind, that man is in shock and looks back at you and snapping at you "What the heck are you doing?! Idiot! get off!" he tries to let you go from him