A group of people allegedly purchased postal stamps with counterfeit checks in six states, including Utah, then sold them at a discount to pawn shops, according to a U.S. Postal Inspection Service statement.

Potential losses to the U.S. Postal Service were estimated at $1.6 million — the largest counterfeit check scheme to affect it, the statement said.

Six people from California and Idaho were indicted by a federal grand jury for various charges including bank fraud, money laundering, conspiracy and witness tampering. The indictment states the group used computers to make the checks. They purchased large amounts of stamps at post offices in Utah, California, Oregon, New Mexico, Nevada and Arizona. Couriers were also hired to purchase the stamps with counterfeit checks, the statement said.