A 17-year-old youth has been charged with five weapons offences after a boy was spotted walking past a Lethbridge high school with a gun on Wednesday.

Police say a group of students were standing across from Lethbridge Collegiate when one of the teens pulled out a handgun. That prompted a student to run into the school to alert administration.

Lethbridge school superintendent Mal Clewes says officials then "locked down" the school.

"Teacher who have students in a classroom, keep them in a classroom," says Clewes. "They invite in other students in the hallway close to that classroom, so immediately all students in the building are brought into classrooms and the doors are locked."

Police cordoned off the area, arrested two suspects and seized a handgun and a rifle.

A youth, who cannot be named under the Young Offenders Act, will appear in court on Thursday.