TUCSON, Ariz. » Five students at a high school in Tucson are in custody for allegedly conspiring to kill another student on campus, and police say they could be charged as adults in the case.

The five were arrested Wednesday night and booked into jail on suspicion of conspiracy to commit first-degree murder.

Police say the arrested Flowing Wells High students are two 17-year-old girls, two 15-year-old boys and an 18-year-old boy.

Officers went to the school Wednesday after another student told Flowing Wells’ administrative staff of the alleged plan.

Detectives did interviews and learned five students were involved in a weeklong plan to kill another student they were having problems with, and one of the five brought a knife to school.

Police say school staff found a knife in the student’s possession.