Five recently graduated high school students have been arrested in connection with pyrotechnic devices found at Wayne Valley High School in mid-June that led to the school's evacuation one day before the start of final exams.
Chief Assistant Prosecutor James Wilson said four 18-year-olds and one 17-year-old — all men — were taken into custody between Tuesday night at 7 p.m. and Wednesday morning 2:30 a.m.
Wilson wouldn't reveal the students' names until a Wednesday afternoon press conference.
He said the students face seven charges, including attempted aggravated arson, possession of weapons for an unlawful purpose and attempting to cause widespread injury or damage.
They also face two counts of burglary for entering the high school twice, in the morning and evening of June 12, the day before the school was evacuated, he said.
Three will be charged as adults. The third 18-year-old will be charged as a juvenile because he was 17 at the time of the crime.
Wilson said the former students placed the devices in the lockers as a joke.
"It started out as a senior prank," he said. "It went above and beyond a senior prank with the potential for widespread damage."
The devices were found after a student noticed their fuses hanging from a locker on the second floor.
The student notified school officials, who noticed similar material coming out of a second locker.
Four bundled devices with fuses, made up of 5- to 6-inch long sticks, were removed by a bomb squad and detonated in a safe area on June 13.
Wilson said officials don't yet know exactly what was in the devices, but said they were "for lack of a better word, smoke bombs."
Officials earlier described the sticks as "pyrotechnic devices," but not dynamite or fireworks.
Passaic County authorities formed a joint task force to find the suspects.
Surveillance tapes from the high school showed two hooded people in the evening of June 12 putting the devices into two lockers as they walked around the school's second floor. The face of one person is obscured by what appears to be a white ski mask; the other appears to be talking on a hand-held phone.
Wilson said police watched hundreds of hours of video tape taken from 108 surveillance cameras at the school and were able to identify students by their clothing.
About 1,400 students were evacuated after the devices were found.
Finals resumed at the school, about 20 miles northwest of New York City, the day after the evacuation.