Authorities have said that they arrested five fifth graders who allegedly planned to attack and bomb a high school in New Jersey.

CBS New York noted that the youths were detained on Wednesday after written notes and other evidence of a planned attack on Clifton High School were discovered by a teacher. Police were then contacted and officials said the children even brought a device containing vinegar and cinnamon to the high school while they visited it on a field trip. That device, however, was deemed to be “nonfunctioning.”

The New York Daily News reported that the four girls and one boy, all students at Clifton Elementary School 11, have since been released to the custody of their parents and are now suspended.

Their names will not be made public because of their ages and so far criminal charges have not formally been filed against the juveniles.

Clifton police believe this was an isolated incident, but the investigation is ongoing.