A student in Phoenix faces "a number of serious felony charges" after police accused him of bringing an AR-15 weapon and ammunition to a high school, authorities said.

Phoenix Police Department officers and two school security officers responded Friday afternoon to a call of a student with a gun on campus, the department said in a news release Saturday.

School administrators called police after learning of a possible weapon at Bostrom High School shortly before 1 p.m., the Phoenix Union High School District said in a statement emailed to CNN.

"During our investigation, we discovered the report was accurate, and local authorities intervened and confiscated the weapon," the school district said in an email.

Arriving officers detained the male juvenile student in the main office of Bostrom High School, authorities said.

Police said they "acted quickly" to arrest the student, who was found to have brought additional ammunition in his lunchbox and backpack, according to the statement.

School administrators placed the campus on lockdown during the investigation, according to the high school district.

The Phoenix Police Department's Crime Gun Intelligence Unit is assisting with the investigation, and the department said it's working closely with school and district officials.

"We commend those who originally reported the possibility of a weapon on school grounds to adults on campus who immediately called police," police said in the statement.

The police did not immediately release information on where the semi-automatic rifle came from and why the student allegedly brought it to campus.

The student's name and age were not released because he is a minor.

His arrest comes days after an 18-year-old man in Farmington, New Mexico, used an AR-15-style rifle and two other guns to shoot and kill three people and injure six others, including two police officers, CNN reported.