A 15-year-old Blaine High School student is being investigated by police in connection with boxes of bullets that were found overnight at the school.
The discovery led school officials to lock down the campus Thursday morning, keeping at least 300 students in their classrooms.
Meanwhile, law enforcement authorities from three counties, bomb-sniffing dogs and school officials conducted an intensive search of school buildings for weapons or ammunition.
Nothing more was found, but the disruption prompted school officials at noon to cancel classes and on-campus activities for the rest of the day.
Blaine teams played scheduled road games Thursday night, however, and Principal Rob Anderson said the school planned to resume a normal schedule today.
"We are confident that [the suspect] acted alone, and at this point I am not concerned about the safety and security of our staff and students," Anderson said Thursday afternoon.
He said that no explicit threat was made against the school, and that students and staffers were never in any danger.
Blaine Police Chief Chris Olson didn't say how police and Anoka County detectives connected the male suspect with the bullets. The student, whom police called "a person of interest," lives in Coon Rapids.