Complex sentence: Walking across the square she looks up at the hotel window and sees the shadow of another couple kissing, when a shot is fired, the window opens, and Carmina, a peasant girl, falls to the ground.
Split into simpler sentences: Walking across the square, she looks up at the hotel window and sees the shadow of another couple kissing. Then a shot is fired, the window opens, and Carmina, a peasant girl, falls to the ground.