Police in Tucson, Arizona, on Wednesday arrested five high school students who they say plotted to kill a classmate, the Los Angeles Times reported.

The suspects – Christopher Gibson, 18; Anastasia Lakin, 17; Jessica Good, 17; Gabriel Quiroga, 15; and Andrew Totten, 15 – allegedly intended to target a student "that they were having problems with," and their plan was "not a random act of violence," authorities said; they have been charged with conspiracy to commit first-degree murder.

The teenagers attend Flowing Wells High School, a public school in a northern section of Arizona's second-largest city. They are accused of getting together before school and during lunch to plot the homicide, CNN noted.

"Each meeting got further involved in the planning process, and the last meeting was when they decided to bring the weapon," said Sgt. Pete Dugan, a spokesman for the Tucson Police Department. "They had even decided where the murder would take place, somewhere off campus. These meetings went on for about a week," Dugan added.

Another student came forward and described the plan to administrators on Wednesday; school officials immediately informed police, and detectives descended on the school to make the arrests, collect evidence and conduct interviews, the sergeant added.

"We were able to stop it before it happened, and it was to the point where we thought it would happen," he said.

Gibson, the only adult suspect, is being held in lieu of $100,000 bond; bail for the rest of the defendants has been set at $25,000 each, records with the Pima County Sheriff's Department show, according to the Los Angeles Times. All suspects were charged as adults, the newspaper added.

Flowing Wells High school senior Levi Timmer told KVOA that he knew Gibson as was shocked by the allegations against him and his other classmates.

Gibson "is a really nice kid," Timmer told the Tucson-based NBC affiliate. "I have known him since junior high. It's just sad, he got caught up with the wrong people. Chris Gibson was a good kid."

Tucson police, meanwhile, are asking anyone with information about the incident to call 911 or (520) 882-7463.