As automatic teller machines become more popular among bank customers, they are becoming popular with robbers, too, according to Montgomery County police.

Since February, police report, ten customers making cash transactions at bank-teller machines in the county have been robbed at gunpoint.

Police arrested two Hyattsville men Monday and charged them with armed robbery after a male customer using a money machine at the Perpetual Savings and Loan at Georgia Avenue and Cameron Street in Silver Spring was forced at gunpoint by two men to withdraw and hand over $100 from the machine.

Police said the two men charged with armed robbery were Michael A. Odon, 22, of 2602 Kirkwood Pl. and Kenneth L. Hall, 32, of 2619 Nicholson St.

In most incidents this year, police said, a thief approaches a victim, shows a handgun and orders the victim to take between $100 and $200 from the machine.

Most of the robberies happened between 9 p.m. and midnight, police said, although one occurred about 7 p.m.

So far, no victim has been physically injured.

A police spokeswoman said bank customers are "vulnerable" and should be aware of the possible danger of using the money machines.

Police advise customers using automatic money machines to look for suspicious people or vehicles in the immediate area before approaching the window.

They also suggest taking another person along as a safety measure. If a person is loitering around the machines, police say customers should notify them by calling 911.

A bank security official said customers have some protection in using the money machines. All customers get a card and a personal identification number, which they are urged to keep separate from the card. If the card is stolen, it cannot be used without the identification number.