STORM LAKE, Iowa (AP) — Authorities in northwestern Iowa say seven students in the Storm Lake School District have been arrested on criminal charges for sharing nude photos on their phones. Police have not named the juveniles, and The Associated Press doesn’t typically name juveniles charged with crimes.

Assistant Storm Lake Police Chief Chris Cole tells the Sioux City Journal that the investigation began Feb. 6, when police were called to Storm Lake High School about multiple students sending nude photographs via text messages to other students.

Authorities say six Storm Lake High School students and one Storm Lake Middle School student were arrested on suspicion of charges ranging from felony exploitation of a minor to misdemeanor dissemination of obscene material to a minor.

Police say several cellphones were seized in the investigation.