Groton — City police on Thursday warned residents of a scam involving someone suggesting he or she is a representative of Groton Utilities.

According to police, the caller threatens to shut off residents’ power, asks residents to get some form of payment card from Stop & Shop — and possibly from other businesses as well — and tells them to call a certain phone number. 

Police said Groton Utilities does not call from toll-free numbers and would never ask residents to use an untraceable payment method.

Groton Utilities’ real number is (860) 446-4000.