You have the crime and the number of characters in which to build a scene. So do it! If I told you to murder 14 people with at least two different weapons and you must have only one main character, could you? Write it out.
So lets start with..
Victims: 8 (adults and children)
Your job is to describe either the crime in process (place, reasoning, witnesses (if there are any). Build a scene! Or you can describe the aftermath, give us a news report or tell the story from the detective's point of view.