QUINCY (CBS) – Quincy police are lauding a good Samaritan who helped save an elderly woman from being scammed out of thousands of dollars in what the police are calling a “textbook grandparent scam.”

Police said Yellow Cab driver Richard Spencer picked up an 87-year-old woman who wanted to go to Walmart. She said she needed to buy gift cards for her grandson who was in trouble.

“I said excuse me ma’am, but that is not your grandson,” Spencer said. “It’s someone posing. And the police officers confirmed that to her that she was being scammed.”

Since another cab driver told him that this woman had bought two gift cards for $2,000 each earlier in the day, Spencer believed the woman was being scammed.

“I don’t think so lady,” Spencer said told the woman. “I think you’re getting scammed. I heard this before, you know.”

Instead of Walmart, he brought her to the Quincy Police Station.

Police discovered a man identifying himself as the woman’s grandson told her that he had been in a car accident and needed gift cards so he wouldn’t go to jail. The caller told the woman how to call a cab, go to the store, purchase gift cards and call back with the gift card pin numbers.

The woman did lose $4,000, but was prevented by losing more money by Spencer.

“I said, no, no we’re not going to Walmart. I’m calling the Quincy Police,” Spencer said. “I said I believe your being scammed and we’re going to try to save you some money.”

In a Facebook post, Quincy police reminded people to be on the lookout suspicious purchases by the elderly.

“Cashiers, etc: If you work in an environment that sells gift cards, take a moment to ask yourself: Does this make sense? Why would an 87-year-old individual need $4,000 in gift cards to this particular store/app? Ask questions. Sure, there may be a legitimate reason, but if you take the time and ask the questions, you just might prevent someone from falling victim.”

The police also went on to praise Spencer.

“Thank you Mr. Spencer for caring. You could have chosen to remain silent and ignore the signs. But you didn’t. And for that we say THANK YOU.”

Quincy Police say scammers typically operate outside of the U.S. and 99.9% of the time, the crook is never caught.

“I think it’s one of the scummiest crimes you can do,” Spencer said. “It just goes to show what scumbags they are, they’re too lazy to go out and steal like a real criminal, they go scam people on the phone.”