Police are expected to file charges against an 11-year-old New Jersey boy after an investigation uncovered an alleged plot to kill 40 classmates, authorities say.

The boy was in the fifth grade at Central Elementary School in Wall Township when school officials found a note containing violent threats in April. Subsequent investigation by police uncovered a more elaborate plan on the boy's computer targeting 40 students, officials said. 

The boy was suspended and barred from enrolling in the district intermediate school for upcoming academic year.

Police said the boy was planning an event "similar to a Columbine or Newtown" at the intermediate school, but that it wasn't something he was capable of carrying out, calling it a "fantasy." 

They added at least one member of the student's family has weapons, but the boy never had access to them. 

In a letter to parents Wednesday, interim superintendent Stephanie Bilenker said "the matter is firmly under control by the law enforcement officials and no present threat exists," she said. 

Bilenker said juvenile charges are expected to be filed against the boy "in the very near future" and that district school officials and police are taking additional steps to ensure students were safe.