Three students were arrested over the weekend for plotting a Columbine-like assault on New Bedford High School.

The students, two of whom were juveniles and 17-year-old Eric McKeehan were arrested when a custodial worker working for New Bedford High School found a letter Tuesday detailing a plot to set off mass explosives at the school and shoot and kill fellow students.

Police in a televised statement explained that the three had planned for the attack to be “bigger than Columbine” and that it was supposed to conclude will all three ending their own lives.

The letter specified that the attack would occur on a Monday but did not give a date.

Area police first began to look into the case when a student warned them on Oct. 17 that McKeehan and some of his friends had been making references to possibly blowing up the school or harming other students. Police later found materials that could be used to make a bomb, but lacked evidence to arrest any of the three.

When the letter was discovered police entered and seized materials used to make bombs, shells used in shotguns and photographs of the three holding weapons from their homes.

Thirty-eight police officers brought in five bomb-sniffing dogs yesterday to look for explosives within the school but found nothing. Police declared the school safe for students to return to.

The high school students now face charges of conspiracy to commit murder, conspiracy to commit assault and battery with a dangerous weapon, and possession of ammunition. They will be arraigned today. McKeehan is being held on $10,000 bail, while the other two youths are being held at $5,000 respectively.

The police have also been in touch with two other students whom they believed were assisting McKeehan and others in their attempts. They have not yet been brought into custody and police maintain that they are not a threat.

The police are also continuing to interview additional individuals that may or may not be involved in the attempt. Police will not comment on the number of potential conspirators only to say that the number is relatively low.

The school has an enrollment of 3,300 students in the approximately 100,000 city of New Bedford. It explains in its mission statement that both administrators and educators alike are committed to providing students with a safe environment in which to learn.

“To this end, the administration, faculty, and staff provide a safe and secure environment in which all students can learn,” the mission statement said. “The school staff, parents, and the community share the mission of helping students become responsible and well rounded citizens.”

The attempted attack on the school is being compared to the incident that occurred in 1999 in Littleton, Colo. Two students, Dylan Klebold and Eric Harris entered Columbine High School armed and wearing black trench coats and opened fire on the student body. More than 20 people were injured and the body count totaled 15, including both alleged killers.

Following that incident has been a rash of other school shooting all over the country. Seven months after Columbine a 12-year-old boy from Deming, N.M. shot and killed a female classmate during lunch recess. He allegedly fired a single shot from a .22 caliber handgun.

A month later, a 13-year-old boy from Fort Gibson, Okla. arrived at his school and opened fire on his classmates using his father’s handgun. Five students were injured in the altercation.

A more recent shooting occurred on March 5 of this year when a 15-year-old boy opened fire on his classmates with a revolver at his high school in Santee, Calif. The student killed two of his classmates and injured 15 others.

Information from Boston.com was used in this story.