article_snippet.sent: The girl, who has not been named but attends school in San Dimas, CaliforniaCalifornia, is the target of disturbing posts on the photo-sharing service.
article_snippet.sent: disturbing posts on the photo-sharing service consist of pictures of A middle school student accompanied by threatening messages.
article_snippet.sent: The above pictures, which showed Unnamed girl's unobscured face, were posted on Instagram along with violent messages .
article_snippet.sent: Investigators believe the threats originate from other school children - though it is unclear whether one or several people are to blame.
article_snippet.sent: According to local news station KTLA, the posts are being removed by Instagram as the posts are reported, but keep cropping up.
article_snippet.sent: Detectives said the social network is co-operating with the posts hunt, but that pinning down whoever is responsible has proved time-consuming.
highlights_snippet.sent: Unnamed girl was targeted by threatening posts on social network .
  
highlights_snippet.sent: Investigators believe fellow students are posting the threats .
  
highlights_snippet.sent: In one message a user threatens to bring a knife to school and stab Unnamed girl .