This is a powerful image for many reasons. The photographer used the rule of thirds and framed the two subjects in the upper portion of the image. The curve of the fence leads the viewers eyes directly to the main subjects of the photo and their bodies are hunched and pointed right to the other important part of the image (the blood splatter, vase, and teddy bear). This allows the viewer to easily place the different aspects of the photo together so they can understand what happened. The blood splatter also points to the two children and brings your eyes there as well.