Looking for a story

Can anyone help please , I'm looking for a story about a young boy who has to stay with friends while his parents fly to a sick parent . The boy has an accident whilst playing in the yard when an elderly neighbour drives into the yard and pins him under the car , the story then revolves around the hospital and the wait for the parents to return which is delayed by 9/11 . I can't remember who it is by or the title just that it is a good read , thanks in anticipation .