Montgomery County police suspect that criminals operating in a parking lot on Rockville Pike tricked two senior citizens into handing over large amounts of money — in one case, $10,000.

In both incidents, the victims — a 68-year-old woman and a 77-year-old man — were approached by two people who persuaded them to withdraw money from their bank accounts and hand it over to the con artists, police said. The criminals then left without keeping a promise to deliver even more money to the victims.

The male victim told police that two men approached him Aug. 6 near the Bank of America in a North Bethesda shopping center and showed him a large amount of money. One told the victim that he did not trust banks, and the victim was persuaded to withdraw $10,000 from a SunTrust Bank branch in Bethesda, police said. Then the two men left.

The female victim was approached July 26 by a man and a woman in the same parking lot but near the Giant supermarket, authorities said. The two con artists told the victim that if she gave them $1,700, they would invest the money and give her $400,000, police said. She complied.

Police provided no further detail on the workings of either con.

Cpl. Rebecca Innocenti said that although the victims fell prey to different pairs of con artists, police believe the two instances of fraud were related. “They often work in a group,” she said. “We have these confidence games from time to time. It follows the same script each time.”

Innocenti said the two people who reported the frauds to police might not have been the only victims of the con artists. “A lot of times, they feel embarrassed and don’t report it to us,” she said.

The shopping center where the encounters took place is in the 12000 block of Rockville Pike.