CLIFTON -- Four grade-school students devised "an immature and unrealistic plot" to bomb Clifton High School in retaliation to a perceived bullying incident by a high school student, authorities said.

The students, who attend School 11 and are 10 and 11 years old, built a "bomb" that consisted of an empty mini Altoids tin containing vegetable oil, salad dressing and cinnamon sticks, Passaic County Prosecutor Camelia M. Valdes said in a news release. It was "neither flammable, nor dangerous, nor did any student possess any type of lighting device," Valdes said.

The students' names were not released because they're juveniles. Valdes didn't comment on the perceived bullying incident that prompted the bomb plot except to say that one of the members of the group knew the high school student.

Clifton police previously said a group of fifth grade students planned to use the device during a field trip to the high school but the plot was uncovered by school officials. Officials later found the group's written plan.

Initially, police said five juveniles were detained over the incident. Jennifer Bedrin, chief assistant prosecutor with the juvenile unit, told NJ Advance Media four juveniles and the high school student were detained by authorities. Neither the fifth-graders nor the high school student were charged.

"At no time were the students of School 11, or Clifton High School in danger," Valdes said. "None of the juveniles were arrested, taken into custody or charged in this matter."

These fifth-graders, however, will be required to undergo mandatory counseling by entering into a station house adjustment agreement with the Clifton Police Department, Valdes said. A station house adjustment is a diversion from formal prosecution and is reserved for first time offenders.

The juveniles will also be required to undergo psychiatric evaluation before returning to school, she said.

"If the juveniles fail to adhere to the counseling condition, or the psychiatric evaluation requirement, the juveniles may face formal charges," Valdes said.

Justin Zaremba may be reached at jzaremba@njadvancemedia.com. Follow him on Twitter @JustinZarembaNJ. Find NJ.com on Facebook.