Hidden cameras have been found attached to ticket vending machines on the Long Island Railroad, and the police are warning customers who have used the machines to check for any unauthorized activity on their credit or debit cards.

The cameras were hidden in thin black strips that were glued on to appear to be part of the machines, the Metropolitan Transportation Authority police said in a statement. Seven machines were affected at Bayside, Great Neck, Merillon Avenue in Garden City and Greenvale.

Such cameras are typically used in conjunction with other electronic devices planted in machines to record banking details and personal identification numbers that enable thieves to make copies of cards and withdraw money. The swindle is most often used on automated teller machines, but recent reports, particularly from Europe, have shown a shift toward ticket and other payment machines.