AMES, Iowa (AP) — Police in Ames are warning of a phone scam targeting Iowa State University students. The Des Moines Register reports that multiple Iowa State students have received calls demanding money. Police say the callers threaten to take a student’s diploma, issue an arrest warrant or cause problems with a visa. Often, the callers mask their phone numbers through caller ID, posing as police departments.

Police are asking on-campus residents who have given money to the callers or who think they have received a call from a scammer to contact ISU Police. Off-campus students are asked to report incidents to the Ames Police Department. All are urged to contact the Federal Trade Commission through the commission’s website.