CARO, Mich. —  Three men were arraigned Saturday on terrorism-related charges after police found about 1,000 cell phones in their minivan.

A magistrate set bond at $750,000 for each of the men, who are charged with collecting or providing materials for terrorist acts and surveillance of a vulnerable target for terrorist purposes.

Officials have declined to say how the case relates to terrorism.

No pleas were entered at the arraignment at a District Court in Caro, about 80 miles north of Detroit, Michigan.

Maruan Awad Muhareb and Louai Abdelhamied Othman, both of Mesquite, Texas, and Adham Abdelhamid Othman, of Dallas, were stopped before dawn Friday after they purchased 80 cell phones from a Wal-Mart in Caro. Police said they found about 1,000 cell phones, mostly prepaid TracFones, in their minivan.

The men cooperated with police and the FBI for hours before their arrests Friday afternoon. They said they intended to sell the phones in Texas for a profit.

Authorities have said TracFones are often used by terrorists because they are not traceable. Cell phones can also be used to make detonators.

Adham and Louai Othman are in their early 20s, and Muhareb is 18. All are being held at the Tuscola County Jail, Caro police said.