NEW YORK ( TheStreet) -- Sony ( SNE) is warning its 77 million users that their private account details, such as passwords, names, birthdates, addresses and credit cards, may have been compromised after the PlayStation Network was infiltrated by an unknown hacker. "We have discovered that between April 17 and April 19, 2011, certain PlayStation Network and Qriocity service user account information was compromised in connection with an illegal and unauthorized intrusion into our network," Sony said. The PlayStation maker said the hackers may have access to customers' vital information. "Although we are still investigating the details of this incident, we believe that an unauthorized person has obtained the following information that you provided: name, address (city, state, zip), country, email address, birthdate, PlayStation Network/Qriocity password and login, and handle/PSN online ID," the company said. "While there is no evidence at this time that credit card data was taken, we cannot rule out the possibility," Sony added. The PlayStation Network, the infrastructure that provides online gameplay and digital shopping for owners of PlayStation 3 and PSP devices, has been down since last week, following what Sony called an "illegal intrusion" on its servers. The company expects to restore "some services" within a week. Sony has temporarily shut down the network and hired an outside security firm "to conduct a full and complete investigation into what happened." In the meantime, the Sony has advised users to change their passwords and warned about phishing scams. "For your security, we encourage you to be especially aware of e-mail, telephone, postal mail or other scams that ask for personal or sensitive information," the company said. "Sony will not contact you in any way, including by e-mail, asking for your credit card number, Social Security number or other personally identifiable information. If you are asked for this information, you can be confident Sony is not the entity asking." Sony shares were falling 2.9% to $28.92 in premarket trading Wednesday. --Written by Theresa McCabe in Boston.