Correction, Friday, 12:29 a.m. EST: A previous version of this story said in the headline that the arrested students were from Clifton High School and the lead paragraph said they were planning to set off an explosive device at School 11. The headline and story have since been corrected to show the arrested students were from the Number 11 Elementary School and that they were planning to set off an explosive device at Clifton High School.

Five schoolchildren from the Number 11 Elementary School in Clifton, New Jersey, were arrested Wednesday after they allegedly tried to “cause damage” or “detonate a device” inside Clifton High School. The children were arrested after teachers and school administrators found letters explaining the alleged plan, WABC, a local ABC News affiliate, reported.

School authorities informed the police after finding the letters, CBS New York reported. Police officials found a “suspicious device” at the school but it was not an explosive.

"It was not a prank," Detective Sgt. Robert Bracken said, according to, a local news website, adding: "They had a legitimate plan."

Police also said that someone may have helped the students formulate the plan, News 12 New Jersey reported.

The children, aged 10 and 11, have been released to their parents and suspended from school, WABC reported. However, no official charges have been filed against them yet. The names of the children will not be made public because of their age, reports said.

Police officials said, according to CBS New York, that this was an isolated incident and there were no safety issues at the school. School authorities have reportedly not commented on the incident.

The latest report comes amid increasing attacks at American schools and colleges. In October, a shooting at Umpqua Community College in Roseburg, Oregon, killed 10 people and left seven injured. In May, a student at a community college shot and stabbed people near the University of California, killing six people and wounding 13 others.