They say it all started Tuesday when students spotted a school shooting threat written on a bathroom wall.
Fresno police investigated and deemed it not to be a credible threat, but news of the threat spread on social media, so students and staff were on edge and at a heightened alert level Wednesday.
In the morning, someone on campus reported suspicious activity when they saw three students carrying around a backpack in an unusual way.
Police took the students into custody, questioned them, and searched the campus for weapons, but later released all three students.
Fresno Unified communications staffers say this was a false alarm. The students were doing something they thought was funny, but it wasn't, and it was considered suspicious, especially in light of the threat one day earlier.