An Iowa power utility is warning residents not to fall for a phone scam that has targeted power customers around the country.

The Des Moines Register reports that MidAmerican Energy has received reports from its customers complaining of suspicious calls.

People posing as electric company employees tell customers they are behind on their bills and must purchase a prepaid debit card, load it with money and hand over the serial number, or else face having their electricity shut off.

The utility is warning customers not to give credit card numbers, account information and personal information.