Patrons of two Sonoma Valley gas stations are urged to defend themselves against fraud after credit card skimmers were found Thursday at both locations.

The devices were first reported by the manager of the Valero station at Highway 12 and Siesta Way, according to the Sonoma County Sheriff’s Office. A deputy recovered five credit card skimmers from that station and from the Beacon station directly across the highway, Sheriff’s Office said.

The skimmers are capable of stealing key credit card information for later fraudulent use.

“It appeared two credit card skimmers had already been removed” by the thieves, sheriff’s officials said in a news release. The skimmers apparently had been there since Oct. 5.

The Sheriff’s Office encouraged customers who used credit or debit cards to pay at the pump at the two stations to cancel the cards and monitor banking records and credit card statements.

Any gas station customers who notice fraudulent activity should call investigators at 707-565-2185 and refer to case No. 181011-023.