Twitter disclosed on Friday evening that its systems had been attacked in the past week by an unidentified group of hackers. As a result of the the attack, the hackers may have had access to the usernames, email addresses and other sensitive information of nearly a quarter of a million twitter users. “This week, we detected unusual access patterns that led to us identifying unauthorized access attempts to Twitter user data. We discovered one live attack and were able to shut it down in process moments later,” the company said in a blog post. “However, our investigation has thus far indicated that the attackers may have had access to limited user information – usernames, email addresses, session tokens and encrypted/salted versions of passwords – for approximately 250,000 users.” Read the full story at All Things D.