Authorities are warning people about an ATM scam that could leave you with an empty bank account.

Thieves gain access to your accounts by pouring glue into an ATM’s card slot, which forces customers to use their cards’ “tap” feature, according to the San Francisco Police Department. However, tapping one’s card works differently than using the slot; after the machine dispenses cash, the transaction window stays open. When a customer fails to notice this, the thief — who’s usually watching from a nearby location — then steps up to the ATM and makes further withdrawals, police say.

One victim, San Francisco resident Joey Mularky, says he actually interacted with the thief before he was ripped off. “It looked like someone had stuffed a gift card in there and it was really sticky,” Mularky says. “He says, ‘Oh — you have to tap your card, because it’s been broken.’ And I was like, ‘Oh, thanks.”

Has anyone ever taken your money by using an ATM?