The elderly Westbrook woman had already started to do the scammer’s bidding when it occurred to her that there was something suspicious about what the person claiming to be from the Internal Revenue Service had told her.

According to what the woman told Westbrook police, she supposedly owed the IRS money, and in order to avoid being arrested, needed to send $9,000 worth of gift cards. She had already bought a few of them, said Westbrook Police Chief Janine Roberts.

“She ended up coming into the police station yesterday evening as she was in the process of collecting the gift cards,” Roberts said Saturday. “Something dawned on her.”

The Westbrook resident, whom Roberts would not identify, arrived at the station asking whether it was true that she might be arrested. Roberts said that an investigation revealed that other local residents may have been subject to the same scam. An investigation found that Hannaford stores and Family Dollar had sold thousands of dollars of gift cards to elderly women earlier in the day.

“I don’t know how many,” Roberts said.

Roberts did not know if only women had been targeted. The woman who came to the station had also been ordered to buy gift cards at Walmart.

On Saturday, Roberts urged local residents to contact police should they receive such a call, and also asked retailers to be wary of large purchases of gift cards and to contact police before completing such a purchase.

It’s likely that the scammers were targeting a region, rather than Westbrook only, Roberts said. “It is also feasible that it was a one-shot deal.”

Police in South Portland and Portland said such scams are common but they did not know of any from the last few days that fit this pattern.

This year, a Falmouth Walmart employee was honored by the company for intervening to prevent a customer from being taken in by a similar scam.