The closeness of family bonds symbolized by the holiday season can create vulnerabilities, as Montgomery County residents have found out recently, according to the county police.

Police said last week that in two cases, $2,000 was sent to swindlers who have been contacting residents of the Friendship Heights area and claiming to be grandchildren in trouble and urgently needing cash.

Since mid-October, police said, about five county residents, most of them elderly, have received calls in which the swindlers claim to be the victims’ grandchildren. The imposters claim that they were arrested or in an accident in Mexico or Canada.

Residents are given the numbers of bank accounts in which to deposit money immediately and are asked not to tell other relatives.

Authorities say swindlers often tell victims that their voices sound different because they have been injured or have fallen ill as a result of of their emergencies.

Police are urging residents to verify the identity of anyone contacting them by telephone.

“Do not send money to anyone you do not know,” police said.