How did the police station know the blocked card number?

Call the service hotline of the issuing bank and ask for manual service. Call the service hotline of the issuing bank and switch to manual service, provide the ID number or bank card number, and ask the customer service to help you find the reason, or bring the bank card to the business hall to find it, and the bank staff will tell you the reason. The bank card was frozen by the public security bureau, probably because the funds in the bank were illegally operated and monitored by the public security organs, so it was frozen.